fix(auth): close what the epic's own review found (E9.5 review round 1)

Eleven findings survived adversarial verification; these are the fixes.

**Address pre-emption.** S1 dropped the approval-time password revoke, arguing `password_login`
refuses an unverified account before it reads `is_active`. Two verifiers showed that holds only
while the address stays unverified — and S6's approval mail exists to get the real owner to end that
state, at which point the squatter's password works. While an address is unverified the NEWEST
registration now owns it: the password is replaced and every outstanding verify token deleted, so
the owner takes the row back simply by registering, and a link already in flight cannot confirm it
for anyone else. The residual (an owner who confirms and neither registers nor resets) is logged as
SEC-16 beside SEC-15, where the re-attestation path it needs already lives. The comments that
asserted the old, false invariant now say what actually guards this.

**The entry URL.** S2 moved `clearEntryUrl()` out of the signed-out auth card into a hook App mounts
unconditionally, and it blanket-stripped the whole query string, the fragment and `history.state` on
the FIRST commit. That broke first-run setup outright — the wizard mounts only after its query
resolves and then finds no `?token=` — and silently ate `?link=`/`?oauth=` (no toast, no refetch
after connecting Google), `?v=`/`?chan=` deep links, and scroll restoration. It now clears only the
fragment and the two one-time flags it owns, and preserves `history.state`.

**The env allow-list.** S3 canonicalised the Invite branch of `is_allowed` and left the
ALLOWED_EMAILS/ADMIN_EMAILS fallback matching literally — the 2026-09-03 lockout with a different
source of truth, plus a shadowing trick where an unauthenticated request under a sibling spelling
permanently masked an env grant. Canonical on both sides now, and the same for the delete dialog's
warning and the ADMIN_EMAILS role bootstrap.

**Honest states.** `send_invitation` stamped "I already wrote to them" before a fail-soft background
send; it sends inline and records only what left. The admin-side resend answered `{ok: true}` for a
dropped mail; it now says so. Both also activate/serialize consistently with the other decide paths.

**Correctness sweep.** The 7-day approval link said "expires in 168 hours" — durations render in
days once there is more than one. `_register_account`, `upsert_pending_invite` and `add_invite`
picked among canonical siblings with no ORDER BY and no exact-spelling tie-break, so which account
got the re-send, and whether a denied row was reopened over a pending one, was up to Postgres.
`purge_user` deleted every canonically-equal invite, revoking a surviving sibling account's access.
`ConfirmProvider` wrapped its ReactNode message in a `<p>`. Approving no longer leaves the
stuck-sign-ups list stale. The refusal panels announce and take focus.

**Tests.** Three mailers rewritten this epic never rendered in any test; every `send_*` now renders
in both languages. The orphan-key guard could not fail (it scanned the catalog that defines the
keys) and had no reverse direction. Newly pinned: canonical activation, the surviving sibling's
grant, a failed invitation and resend, an expired reset link, a throttled login's silence, the
per-language admin fan-out, and that the entry URL keeps what it does not own.

backend/tests/test_mail_language.py

@@ -7,6 +7,7 @@ language a given recipient actually gets, and where that signal was captured, si
 with no account it exists only at the moment they asked us.
 """
 
+import re
 import string
 
 import pytest
@@ -42,15 +43,38 @@ def test_every_translation_takes_the_same_placeholders(key):
         assert _placeholders(template) == expected, f"{key} [{lang}]"
 
 
-def test_no_catalog_entry_is_orphaned():
-    """Every key is referenced from the app, so a mail that stopped being sent can't leave its text
-    behind to be 'kept up to date' by the next person who greps for it."""
+def _app_sources_without_the_catalog() -> str:
+    """Every app source, with the catalog LITERAL cut out of mailtext.py.
+
+    Cutting it is the whole point: the dict spells each key as a quoted literal, so a scan that
+    included it reported every key as used no matter what the catalog held. Cutting the whole FILE
+    is too much, though — `link_expiry` legitimately asks for `duration.*`, and those keys would
+    then look orphaned."""
     from pathlib import Path
 
     app_dir = Path(__file__).resolve().parents[1] / "app"
-    sources = "\n".join(p.read_text(encoding="utf-8") for p in app_dir.rglob("*.py"))
-    unused = [k for k in mailtext.MAIL_TEXT if f'"{k}"' not in sources]
-    assert unused == []
+    out = []
+    for f in app_dir.rglob("*.py"):
+        src = f.read_text(encoding="utf-8")
+        if f.name == "mailtext.py":
+            src = src[: src.index("MAIL_TEXT: dict")]
+        out.append(src)
+    return "\n".join(out)
+
+
+def test_no_catalog_entry_is_orphaned():
+    """Every key is referenced from the app, so a mail that stopped being sent can't leave its text
+    behind to be 'kept up to date' by the next person who greps for it."""
+    sources = _app_sources_without_the_catalog()
+    assert [k for k in mailtext.MAIL_TEXT if f'"{k}"' not in sources] == []
+
+
+def test_every_key_the_app_asks_for_exists():
+    """The other direction, and the one that raises in production: `text()` looks the key up in a
+    dict, so a renamed or mistyped key is a KeyError inside a background task with no user in sight."""
+    asked = set(re.findall(r'text\(\s*"([a-z_]+\.[a-z_]+)"', _app_sources_without_the_catalog()))
+    assert asked, "the scan found no mailtext.text(...) call sites — the pattern has rotted"
+    assert sorted(asked - set(mailtext.MAIL_TEXT)) == []
 
 
 def test_an_unknown_language_falls_back_to_english_instead_of_raising():
@@ -157,7 +181,9 @@ def _bodies(monkeypatch):
 
     out: list[tuple[list[str], str, str]] = []
     monkeypatch.setattr(
-        email_mod, "_send", lambda to, subject, body, reply_to=None: out.append((to, subject, body))
+        email_mod,
+        "_send",
+        lambda to, subject, body, reply_to=None: out.append((to, subject, body)) is None,
     )
     return out