Docs: catch up to auth discovery, settings screen and sync fixes

Document the four features that landed on main in b44bc8c..85c790e:

- AGENTS.md: post-MVP section now covers server-driven auth discovery
  (GET /api/config, AUTH_PASSWORD_ENABLED 403 enforcement,
  OIDC_GENERIC_DISPLAY_NAME), the settings screen with GET/PUT /api/me,
  and the critical Android sync/data-safety fixes (pull-all-lists,
  client HLC tick per server op, no destructive migration, ProGuard
  rules). Repo structure updated (httpapi config.go/me.go, ui/settings),
  roadmap entries added, open-points list extended with test backlog for
  the new endpoints.
- API.md: new sections for GET /api/config (public) and GET/PUT /api/me;
  403 responses documented for register/login when password auth is off.
- SYNC.md: client pull loop (every tracked list, op_log pruning) and the
  client HLC discipline (tick per incoming server op) that keeps LWW
  correct across devices with skewed clocks.
- README: highlights for auth discovery/OIDC-only mode and the settings
  screen.

docs/SYNC.md

@@ -56,6 +56,17 @@ All state modifications are represented as structured operations:
   Each operation carries a `(client_id, client_seq)` tuple enforced by a `UNIQUE` constraint in Postgres (`op_log`). Re-sent requests return previous `(seq, hlc_ts)` assignments without duplicating side effects.
 - **Cursor Pull (`GET /api/lists/{id}/ops?since={seq}`)**:
   Clients track `max(server_seq)` locally. Incremental sync fetches ops where `seq > cursor`, sorted by monotonic server sequence `seq ASC`.
+- **Client pull loop**:
+  The `SyncWorker` pulls for **every** tracked list on each run (not only lists with pending outbox ops), so remote edits on "quiet" (e.g. shared/joined) lists arrive reliably. Old synced `op_log` rows are pruned locally to bound growth.
+
+### Client HLC discipline
+
+On every incoming server op the client advances its local HLC with
+`tick(op.hlc_ts)`. This is essential for LWW correctness across devices with
+skewed clocks: without it, a fast-clock device would permanently win conflicts
+while a slow-clock device's own edits would be silently rejected by the
+`hlc_ts <` projection guard. The same rule applies on the server (`opstore`
+ticks the server HLC per incoming op).
 
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