Add self-service password change, forgot-password flow, and fix admin UI bugs

Users can change their own password from the profile modal, and a
"forgot password" link sends a 15-minute expiring reset link (same
hashed-token pattern as site invites). The forgot-password response is
always generic so it never reveals which emails are registered.

Also fixes two admin-page display bugs found while testing: table row
divider lines that didn't line up across a row (the actions column had
`display: flex` on the <td> itself, breaking it out of normal table-cell
layout -- moved to a child <div>), and the pending-invites list floating
with no visual grouping (now boxed with a label and per-status badges).

backend/app/models/__init__.py

@@ -7,6 +7,7 @@ from app.models.membership import RoomMembership, RoomRole
 from app.models.message import Message
 from app.models.message_image import MessageImage
 from app.models.message_reaction import MessageReaction
+from app.models.password_reset import PasswordReset
 from app.models.push_subscription import PushSubscription
 from app.models.room import Room
 from app.models.site_invite import SiteInvite
@@ -24,6 +25,7 @@ __all__ = [
     "MessageImage",
     "MessageReaction",
     "InviteStatus",
+    "PasswordReset",
     "SiteInvite",
     "SmtpSettings",
     "PushSubscription",

backend/app/models/password_reset.py

@@ -0,0 +1,33 @@
+import uuid
+from datetime import datetime, timedelta, timezone
+
+from sqlalchemy import Boolean, DateTime, ForeignKey, String, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+DEFAULT_RESET_LIFETIME = timedelta(minutes=15)
+
+
+def _default_expires_at() -> datetime:
+    return datetime.now(timezone.utc) + DEFAULT_RESET_LIFETIME
+
+
+class PasswordReset(Base):
+    __tablename__ = "password_resets"
+
+    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
+    user_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("users.id"), index=True, nullable=False)
+    # Same convention as SiteInvite.token_hash / API tokens: a bearer secret
+    # looked up by itself, so it's hashed with security.hash_token (fast,
+    # deterministic sha256), not argon2.
+    token_hash: Mapped[str] = mapped_column(String(64), unique=True, index=True, nullable=False)
+    used: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    expires_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=_default_expires_at, nullable=False
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+
+    user = relationship("User")

backend/app/routers/auth.py

@@ -1,16 +1,25 @@
-from fastapi import APIRouter, Depends, File, HTTPException, Request, Response, UploadFile
+from fastapi import APIRouter, Depends, File, HTTPException, Query, Request, Response, UploadFile
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.database import get_db
 from app.dependencies import get_current_user
 from app.models import User
 from app.schemas.auth import LoginRequest
+from app.schemas.password import ForgotPasswordRequest, PasswordChange, ResetPasswordComplete
 from app.schemas.user import ProfileUpdate, UserRead
 from app.services.auth_service import (
     AccountDeactivatedError,
     InvalidCredentialsError,
     authenticate_user,
 )
+from app.services.password_service import (
+    InvalidCurrentPasswordError,
+    PasswordResetInvalidError,
+    change_password,
+    complete_password_reset,
+    request_password_reset,
+    validate_reset_token,
+)
 from app.storage import (
     ALLOWED_IMAGE_CONTENT_TYPES,
     ImageTooLargeError,
@@ -120,3 +129,55 @@ async def remove_avatar(
         delete_image(previous_filename)
 
     return current_user
+
+
+@router.patch("/password", status_code=204)
+async def change_password_endpoint(
+    data: PasswordChange,
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+) -> Response:
+    try:
+        await change_password(db, current_user, data.current_password, data.new_password)
+    except InvalidCurrentPasswordError:
+        raise HTTPException(status_code=400, detail="Current password is incorrect")
+    return Response(status_code=204)
+
+
+@router.post("/forgot-password", status_code=204)
+async def forgot_password_endpoint(
+    data: ForgotPasswordRequest,
+    request: Request,
+    db: AsyncSession = Depends(get_db),
+) -> Response:
+    # Always 204, whether or not the email matched an account -- the
+    # response must not reveal which emails are registered.
+    await request_password_reset(db, data.email, str(request.base_url))
+    return Response(status_code=204)
+
+
+@router.get("/reset-password/validate", status_code=204)
+async def validate_reset_password_endpoint(
+    token: str = Query(...),
+    db: AsyncSession = Depends(get_db),
+) -> Response:
+    try:
+        await validate_reset_token(db, token)
+    except PasswordResetInvalidError:
+        raise HTTPException(status_code=400, detail="This reset link is invalid or has expired")
+    return Response(status_code=204)
+
+
+@router.post("/reset-password", response_model=UserRead)
+async def complete_reset_password_endpoint(
+    data: ResetPasswordComplete,
+    request: Request,
+    db: AsyncSession = Depends(get_db),
+) -> User:
+    try:
+        user = await complete_password_reset(db, data.token, data.new_password)
+    except PasswordResetInvalidError:
+        raise HTTPException(status_code=400, detail="This reset link is invalid or has expired")
+
+    request.session["user_id"] = str(user.id)
+    return user

backend/app/schemas/password.py

@@ -0,0 +1,15 @@
+from pydantic import BaseModel, EmailStr, Field
+
+
+class PasswordChange(BaseModel):
+    current_password: str
+    new_password: str = Field(min_length=8, max_length=200)
+
+
+class ForgotPasswordRequest(BaseModel):
+    email: EmailStr
+
+
+class ResetPasswordComplete(BaseModel):
+    token: str
+    new_password: str = Field(min_length=8, max_length=200)

backend/app/services/password_service.py

@@ -0,0 +1,78 @@
+import secrets
+from datetime import datetime, timezone
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import PasswordReset, User
+from app.security import hash_password, hash_token, verify_password
+from app.services.email_service import send_email
+
+
+class InvalidCurrentPasswordError(Exception):
+    pass
+
+
+class PasswordResetInvalidError(Exception):
+    pass
+
+
+async def change_password(
+    db: AsyncSession, user: User, current_password: str, new_password: str
+) -> None:
+    if not verify_password(current_password, user.password_hash):
+        raise InvalidCurrentPasswordError()
+    user.password_hash = hash_password(new_password)
+    await db.commit()
+
+
+async def request_password_reset(db: AsyncSession, email: str, base_url: str) -> None:
+    # Always returns normally, whether or not the email matched an account --
+    # the router never reveals which, to avoid leaking registered emails.
+    result = await db.execute(
+        select(User).where(User.email == email, User.is_active.is_(True))
+    )
+    user = result.scalar_one_or_none()
+    if user is None:
+        return
+
+    raw_token = secrets.token_urlsafe(32)
+    db.add(PasswordReset(user_id=user.id, token_hash=hash_token(raw_token)))
+    await db.commit()
+
+    reset_link = f"{base_url.rstrip('/')}/reset-password?token={raw_token}"
+    await send_email(
+        db,
+        email,
+        "Reset your KeepItTalking password",
+        f"Someone requested a password reset for this account.\n\n"
+        f"Reset it here:\n{reset_link}\n\n"
+        f"This link expires in 15 minutes. If you didn't request this, "
+        f"you can ignore this email.",
+    )
+
+
+async def _get_valid_reset(db: AsyncSession, token: str) -> PasswordReset:
+    result = await db.execute(
+        select(PasswordReset).where(PasswordReset.token_hash == hash_token(token))
+    )
+    reset = result.scalar_one_or_none()
+    if reset is None or reset.used:
+        raise PasswordResetInvalidError()
+    if reset.expires_at <= datetime.now(timezone.utc):
+        raise PasswordResetInvalidError()
+    return reset
+
+
+async def validate_reset_token(db: AsyncSession, token: str) -> None:
+    await _get_valid_reset(db, token)
+
+
+async def complete_password_reset(db: AsyncSession, token: str, new_password: str) -> User:
+    reset = await _get_valid_reset(db, token)
+    user = await db.get(User, reset.user_id)
+    user.password_hash = hash_password(new_password)
+    reset.used = True
+    await db.commit()
+    await db.refresh(user)
+    return user