feat(run): screenshot attach, Telegram ok:false fix, post-FIRE catchup guard

Three bundled fixes on the dispatch + FSM + notifier triangle:

1. Telegram silent-success bug: parse JSON body after 200 OK, raise on
   ok:false so FanoutNotifier retries + DLQs + stats surface the failure.
   Previously Discord succeeded while Telegram silently dropped.

2. Per-kind screenshot attach: new AlertsCfg dataclass with per-kind toggle
   (late_start, catchup, arm, prime, trigger). _save_annotated_frame helper
   extracted from inline FIRE block, threaded via Snapshot closure into
   _handle_tick. Failures audit-logged, never silent.

3. Post-FIRE catchup regression (d7305fb): residual dark_green/dark_red dots
   after a FIRE cycle look like startup-catchup from (color, state) alone.
   New fsm.fired_in_session(direction) gate suppresses synth-arm after a
   cycle already fired in that direction. Opposite direction unaffected.

Also: queue-overflow on_drop audit callback, periodic + shutdown heartbeat
stats per-backend, config back-compat (bool or dict for attach_screenshots).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -181,6 +181,7 @@ atm report --week 2026-16        # weekly win rate + R PnL + slippage
 | `WARN: no window contains 'xxx'` at startup | `cfg.window_title` substring matches nothing | Edit `window_title` in TOML to a substring that's unique to TradeStation. |
 | No alerts even after trigger ought to fire | Check `logs/YYYY-MM-DD.jsonl` for `event=tick` entries — are colours accepted? Is `trigger` ever set? | If always UNKNOWN → tolerances too tight. If `trigger` but `locked=true` → lockout from prior fire, normal. |
 | Discord OK, Telegram silent (or vice versa) | `logs/dead_letter.jsonl` contains failed alerts with error | Fix credentials in TOML, restart. |
+| Heartbeat shows `telegram: failed > 0` | Telegram returned `ok:false` (bot blocked, invalid chat_id, parse error) | Check `logs/dead_letter.jsonl` for the `error_str` / `description` field. Common: bot never started by user in Telegram, or wrong `chat_id` flavor (channel vs group vs DM). |
 | Debug circle on mid-strip instead of right edge | Anti-aliasing bridges dots in the mask | Already fixed via erosion+connected-components — ensure `git pull` is current. |
 | Wizard window is tiny / image not visible | Tk geometry default on Windows | Already fixed — `git pull`. Image is scaled to fit screen. |