feat(achievements): wall sync drain worker + review fixes (epic PR3) (#592)

* feat(achievements): wall sync drain worker (epic PR3, client side)

Background dead-letter worker that POSTs queued Feat unlocks/removals to the
hosted feedback-achievements wall. Idle unless FEEDBACK_ACHIEVEMENTS_WALL_URL
is set; uses requests + the client-token header (mirrors lyrics_transcribe).

Dead-letter, never drop (pure engine.drain_decision):
  network err / 429 / 5xx -> keep pending (retry)
  other 4xx               -> dead_letter (diagnosable, replayable)
  2xx                     -> delete on server ack
remove-me enqueues a wall removal keyed by the reused player_hash.

Verified by an end-to-end staging round-trip (earn a Feat -> drains onto the
wall with name + short hash -> remove-me -> wall empties) with no IP in tables
or access logs. 42 plugin tests pass (test_sync.py adds the decision table +
ack/retry/dead-letter retention + four-field on-the-wire payload).

The hosted service lives in the new feedback-achievements repo.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(achievements): address local review findings (epic)

Bugs caught in the pre-merge review loop:

- secret_witching Feat was DEAD: post_activity wrote witching_nights_run to the
  DB before snapshotting prev_tiers, so diff_unlocks never saw the fresh unlock.
  Fold the run into the activity delta instead (same asymmetry chart_encore
  uses) so the 7th-night unlock is detected. +regression tests.
- chart_encore broke across restarts: per-chart counter keyed on abs(hash(str)),
  which Python salts per-process (PYTHONHASHSEED). Use a stable sha1 digest so
  the same chart accumulates across sessions. +regression test.
- Bounded the per-activity counter read: _read_counters no longer pulls the
  unbounded chart_plays:* rows (they're bumped/read individually).
- screen.js: gate note:hit/miss on an active-song flag so tuner/calibration note
  events can't inflate Feats or flush a phantom chart:null session.
- screen.js: P-III — prefix the plugin localStorage key (achievements:profile-cat).
- screen.js: extract the duplicated local-ISO-date helper.

45 plugin tests pass (3 new). Wall-side review fixes are in the
feedback-achievements repo.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* feat(achievements): default the drain worker to the hosted wall

Point FEEDBACK_ACHIEVEMENTS_WALL_URL's default at the live got-feedback wall
(https://feedback-achievements.onrender.com) so the drain worker targets it out
of the box; still env-overridable for self-hosting/staging. Nothing publishes
unless the user opted in AND has a profile identity, so a default URL alone
sends nothing.

Tests disable the default (autouse fixture) so no test ever POSTs to production;
drain logic is covered via _drain_once() with an injected poster. 45 pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/plugins/achievements/conftest.py

@@ -10,6 +10,17 @@ from fastapi.testclient import TestClient
 import routes as ach_routes
 
 
+@pytest.fixture(autouse=True)
+def _no_live_drain():
+    # routes now defaults the wall URL to the live onrender service, so setup()
+    # would auto-start the drain thread. Disable it for every test so no test
+    # ever POSTs to production; the drain logic is exercised via _drain_once()
+    # with an injected poster instead.
+    ach_routes._WALL_URL = ""
+    ach_routes._drain_started = False
+    yield
+
+
 @pytest.fixture
 def client(tmp_path):
     app = FastAPI()