fix: security & privacy (rate limiter fix, csrf session cookie, logout on server, drafts stale token passw, login timing, password over 72b, JWT_SECRET complexity, SMTP TLS, CSV export neutralised, fonts bundled, upload metadata, hourly cleanup job, privacy.md report)

docs/architecture.md

@@ -55,6 +55,14 @@ The use cases `GetPurgeSettings`, `UpdatePurgeSettings`, `PreviewPurge` and `Run
 | `GET /v1/media/purge-preview` | Groups, copies, distinct articles, the first 5 groups, `more` and the fingerprint. |
 | `POST /v1/media/purge` | Runs the purge. Optional `fingerprint`; 409 when stale or when a run is in progress. |
 
+### Sessions and personal data retention
+
+A session is an HS256 token from `api/pkg/authtoken`. `Encode` adds a random `jti` and an `exp` 24 hours ahead; `Decode` refuses a token without `exp`. `authtoken.WithRevocationStore` plugs in `useCases.SessionRevocationUseCase`, which stores a `session.Revocation` (`jti`, `exp`) through the `internal/domain/session` `Repository` (`persistence.RevokedSessionRepository`, table `revoked_sessions`). `LoginHandler.Logout` revokes the presented token; from then on `Decode` answers `ErrRevoked` for it, and a store that cannot be read makes every token invalid rather than valid. Revoking every session of a user stays the job of `token_version`, bumped by a password reset.
+
+`useCases.EnforceRetentionUseCase.Tick(now)` deletes revocations past their expiry, unverified accounts 7 days after their code expired (`user.UnverifiedRetention`) and invites 30 days after they expired or were accepted (`invite.Retention`), and returns a `retention.Result`. `scheduler.NewSystemRetentionRunner` calls it one minute after startup and then hourly, logs one line only when something was removed, and stops with the other runners on shutdown.
+
+Uploads go through the `image.MetadataStripper` port before they are measured for size, hashed and stored. `imaging.MetadataStripper` walks the JPEG segments, PNG chunks and WebP RIFF chunks without re-encoding pixels, drops metadata, keeps colour profiles and re-adds an orientation-only EXIF block when the photo was rotated. A container it cannot walk fails the upload with `image.ErrImageUnreadable`.
+
 ### Activity log
 
 `internal/domain/audit` holds the append-only `Event` (actor, target and failure-reason snapshots, outcome, security flag, source, ip, user agent, `params` and `changes`), the closed vocabularies (actor type, category, outcome, source, change kind), the `Filter`, `Summary` and `Settings` types, the `Repository` interface (`Append`, `List`, `Summary`, `DeleteOlderThan`: no way to edit or delete one event), the `SettingsRepository` (`Get`, `SaveRetention`, `SaveLastCleanup`; no row means 90 days) and the sentinels `ErrInvalidFilter`, `ErrInvalidRetention`, `ErrInvalidEvent` and `ErrActorNotAllowed`. The `Recorder` port is `Record(ctx, event)`; it returns nothing, so a caller can never fail on it.