fix(auth): stop the address-bar mirror eating emailed auth tokens, and unlock revoked accounts

Two independent bugs made an email+password registration unrecoverable in prod.

The verification link did nothing. urlWithParams/clearParams rebuilt the URL as
pathname+query and dropped the fragment — but the one-time auth tokens ride the
fragment (#verify=/#reset=, SB3), and the providers that mirror nav params
(useUrlMirror in FeedFilters/Playlists/Plex/Channels) sit ABOVE the lazily-loaded
<App> in main.tsx. Their mount effect replaceState'd the token away before the auth
card's chunk had loaded, so the card read an empty hash: the link opened a bare
sign-in page, no request, no banner. Both helpers now carry the fragment over.

The account was then locked out for good. SEC-10 nulls password_hash when an
unverified account is attested (here: admin approval landing before the user could
verify — which the bug above made impossible). That is indistinguishable from a
Google-only account, and reset eligibility keyed off password_hash alone, so no
reset link was ever issued: no password to sign in with, and no way to get one.
users.password_revoked_at records the revocation, reset eligibility honours it, and
setting a password again (reset-confirm or set-password) clears it. An account that
never had a password stays ineligible on purpose — its owner adds one from Settings.

/auth/verify now also answers password_reset_required so the card can say why the
registered password stopped working, instead of leaving the user at the uniform
"Invalid email or password". Telling the holder of a valid verify token leaks
nothing: they have already proved they own the mailbox.

The 0078 migration backfills the stamp for rows carrying the exact lockout signature
(local, non-demo, no password, unverified), so existing victims recover unaided.

backend/app/routes/auth.py

@@ -662,15 +662,22 @@ def _register_account(email: str, password: str) -> None:
 @router.post("/verify")
 def verify_email_confirm(body: TokenIn, db: Session = Depends(get_db)) -> dict:
     """Confirm an email-verification token the SPA read from the URL fragment (SB3). Uniform 400
-    on any invalid/expired/used token."""
+    on any invalid/expired/used token.
+
+    `password_reset_required` tells the SPA to send the user straight to the reset flow: an admin who
+    approved this account BEFORE it was verified tripped SEC-10, so the password chosen at registration
+    is gone and sign-in would answer with the deliberately uniform "Invalid email or password" — true,
+    but unreadable to the person who just proved they own the mailbox. Saying so leaks nothing: holding
+    a valid single-use verify token for this account already proves that much."""
     user = _consume_token(db, body.token, "verify")
     if user is None:
         raise HTTPException(
             status_code=400, detail="This verification link is invalid or has expired."
         )
     user.email_verified = True
+    needs_password = user.password_hash is None and user.password_revoked_at is not None
     db.commit()
-    return {"ok": True}
+    return {"ok": True, "password_reset_required": needs_password}
 
 
 @router.post("/verify/resend")
@@ -714,8 +721,10 @@ def verify_email(token: str, db: Session = Depends(get_db)):
     if user is None:
         return RedirectResponse(url="/?verify=invalid")
     user.email_verified = True
+    needs_password = user.password_hash is None and user.password_revoked_at is not None
     db.commit()
-    return RedirectResponse(url="/?verify=ok")
+    # Same two outcomes as the POST flow above, so an old link in flight lands on the same guidance.
+    return RedirectResponse(url="/?verify=" + ("ok_reset" if needs_password else "ok"))
 
 
 @router.post("/password-login")
@@ -780,10 +789,18 @@ def _send_reset_if_eligible(email: str) -> None:
     """Background worker for password_reset_request: issue a reset token + email the link, but ONLY
     for a real (non-demo) password account. Runs after the response with its own DB session, so the
     request's timing never reveals whether the account exists. Token rides the URL FRAGMENT (#) so it
-    can't leak into proxy/access logs or a Referer (SB3)."""
+    can't leak into proxy/access logs or a Referer (SB3).
+
+    "Password account" is `password_hash OR password_revoked_at` — an account SEC-10 stripped had a
+    password and must be able to get a new one, or it is locked out permanently (no password to sign in
+    with, and formerly no reset link either). A Google-only account that never had a password stays
+    ineligible on purpose: its owner adds one from Settings (/auth/set-password) while signed in, which
+    proves identity through the session rather than by mail."""
     with SessionLocal() as db:
         user = db.execute(select(User).where(User.email == email)).scalar_one_or_none()
-        if user is not None and user.password_hash and not user.is_demo:
+        if user is None or user.is_demo:
+            return
+        if user.password_hash or user.password_revoked_at:
             raw = _issue_token(db, user, "reset", RESET_TTL)
             email_mod.send_password_reset(email, f"{_app_base()}/#reset={raw}")
 
@@ -802,6 +819,7 @@ def password_reset_confirm(body: TokenPasswordIn, db: Session = Depends(get_db))
     if user is None:
         raise HTTPException(status_code=400, detail="This reset link is invalid or has expired.")
     user.password_hash = hash_password(new_password)
+    user.password_revoked_at = None  # the account has a password again — SEC-10's trace is spent
     # A valid reset link proves control of the mailbox, so completing a reset also verifies the
     # email — this rescues an account that registered but never clicked the verification link (it
     # can then sign in). The separate admin-approval gate (is_active) is deliberately NOT touched
@@ -844,9 +862,15 @@ def revoke_preset_password_if_unverified(user: User) -> None:
     ownership is finally attested (Google adoption, or admin approval), drop that password and bump the
     epoch to revoke any session it minted; the owner re-sets one via password-reset. No-op for an
     already-verified account, so a legit no-SMTP registration is unaffected. The single source for this
-    rule — both the Google-callback and admin-activation paths call it so they can't drift."""
+    rule — both the Google-callback and admin-activation paths call it so they can't drift.
+
+    `password_revoked_at` is what makes "the owner re-sets one via password-reset" actually true. The
+    revoke leaves `password_hash IS NULL`, which is also what a Google-only account looks like — and
+    _send_reset_if_eligible keyed off exactly that, so a revoked account silently got no reset link and
+    was locked out for good (it could not sign in either). The stamp separates the two cases."""
     if not user.email_verified:
         user.password_hash = None
+        user.password_revoked_at = datetime.now(timezone.utc)
         bump_session_epoch(user)
 
 
@@ -916,6 +940,7 @@ def set_password(
         if not verify_password(body.current_password or "", user.password_hash):
             raise HTTPException(status_code=403, detail="Current password is incorrect.")
     user.password_hash = hash_password(new_password)
+    user.password_revoked_at = None  # same as the reset path: a password exists again
     # SA4: a password change logs out every OTHER session; re-stamp this cookie at the new epoch so
     # the person making the change stays signed in here. Commit BEFORE re-stamping so a failed commit
     # can't leave the cookie at a newer epoch than the DB (which would wrongly 401 THIS session).