Narrow the fix to secret material and stop reverting #45947.
The earlier revision added every read-denied name to the write denylist,
which re-blocked auth.json and webhook_subscriptions.json and rewrote the
test guarding them. #45947 freed those control files deliberately:
containment belongs in Docker/remote backends and OS permissions, not an
expanding hardcoded denylist.
What #45947 kept blocked is secret material, and that list had drifted:
auth/google_oauth.json (OAuth token store), the plaintext Bitwarden cache,
vault/ (key + ciphertext side by side) and browser-profile/ (copied
cookies / Login Data) were writable via write_file / patch.
- Write-deny those four; control files stay writable and read-denied.
- _WRITE_DENIED_SECRET_DIRS is its own tuple rather than _READ_DENIED_DIRS,
so a future read-only convenience deny cannot silently become a write deny.
- tests/tools/test_write_deny.py is restored unchanged from main.
- New tests pin both halves: secrets denied, control files writable, and
write denies stay a subset of read denies.
Fixes#110464
NUXER
1c0d95badb