chore: remove the Python service; Python is the training stack only

Phase 4 of docs/RUST_REWRITE.md. Since 2026-10-18 ping-collector (rust/)
collects, forecasts, notifies (ntfy + Matrix) and serves the website/API;
nothing in production ran the Python service code any more.

Removed (~17k lines): the FastAPI app (web_api, schemas, health_check,
metrics, postgres_history, forecast_history, thaiwater), the Python RID
collector and CLI (water_scraper_v3, main, run.py), the notifier and Matrix
alerting (notify, alerting), the multi-backend adapters (SQLite, MySQL,
InfluxDB, VictoriaMetrics) with demo databases, models/validators/exceptions/
logging/rate limiter, ml/skill.py (served by Rust now), the migration tooling
(api_parity, collector_parity, e2e_notify, install_collector.sh,
gen_notify_cases.py, spikes/rust-forecast), Docker/compose/Grafana files,
sql/, the release workflow and the docs for all of that. Their tests went
with them.

Kept in Python: src/ml (training, evaluation harness, export; predict.py as
the reference the Rust forecaster is tested against), the HII and RID-dam
clients/stores for the archive backfills (their live collectors removed),
the backfill scripts, retrain.sh + timer, forecast_parity.py.

- PostgreSQL only: src/config.py is database_url() from POSTGRES_* / .env;
  the stores lost their sqlite/mysql branches (and the 2026-08 column
  migration). The database tests run against a throwaway schema from
  TEST_DATABASE_URL (tests/conftest.py pg_url, skipped without it), as the
  Rust tests do; CI gets a PostgreSQL service. 100 tests (66 without a DB).
- The notifier settings moved from src/notify.py into src/ml/export.py;
  flood_config.json regenerates byte-identical.
- tests/test_dashboard.py checks every path the dashboard fetches against
  ping-collector's router.
- Dependencies: fastapi, uvicorn, pydantic, influxdb, pymysql, psutil,
  schedule, sphinx, pyinstaller, mypy, pytest-asyncio dropped; python-dotenv
  1.1.1 explicit (it came in through uvicorn[standard]).
- Formatting contract extended to scripts/ and tests/ (reformatted once).
- scripts/install.sh is the one installer (fresh host or update, in place in
  a checkout without touching its ownership): binary, units, uv sync, .env
  defaults, removes the retired water-monitor.service and any old
  --alert-check cron job, dry run + forecast check, restart, readiness wait.
- Docs, CLAUDE.md, CONTRIBUTING.md, .env.example, Makefile, unit comments
  and Rust doc comments updated to the Rust service.

scripts/summarize_eval.py

@@ -25,7 +25,8 @@ def summarize(paths):
             for fold in station["folds"]:
                 for name, m in fold["variants"].items():
                     a = agg.setdefault(
-                        name, {"mae": [], "mae_hi": [], "brier": [], "fa": 0, "events": []}
+                        name,
+                        {"mae": [], "mae_hi": [], "brier": [], "fa": 0, "events": []},
                     )
                     a["mae"].append(m["mae"])
                     if m.get("mae_above_2p5") is not None:
@@ -39,8 +40,18 @@ def summarize(paths):
                             if e["peak_pred_24h_before"] is None
                             else e["peak_pred_24h_before"] - e["peak_level"]
                         )
-                        a["events"].append((fold["year"], e["crossing"][:10], e["lead_h"], e["peak_level"], err))
-            print(f"{'variant':22} {'MAE':>6} {'MAE_hi':>7} {'Brier':>7} {'FA':>3}  events: year crossing lead_h peak(err24h)")
+                        a["events"].append(
+                            (
+                                fold["year"],
+                                e["crossing"][:10],
+                                e["lead_h"],
+                                e["peak_level"],
+                                err,
+                            )
+                        )
+            print(
+                f"{'variant':22} {'MAE':>6} {'MAE_hi':>7} {'Brier':>7} {'FA':>3}  events: year crossing lead_h peak(err24h)"
+            )
             for name, a in agg.items():
                 ev = "  ".join(
                     f"{y} {d} {'—' if l is None else format(l, '+.0f')}h {p:.2f}({'—' if err is None else format(err, '+.2f')})"
@@ -54,8 +65,10 @@ def summarize(paths):
                     f"{a['fa']:>3}  {ev}"
                 )
                 if leads:
-                    print(f"{'':22} lead: mean {statistics.mean(leads):+.1f} h, min {min(leads):+.0f} h, "
-                          f"missed {sum(1 for *_, l, _, _ in a['events'] if l is None)}/{len(a['events'])}")
+                    print(
+                        f"{'':22} lead: mean {statistics.mean(leads):+.1f} h, min {min(leads):+.0f} h, "
+                        f"missed {sum(1 for *_, l, _, _ in a['events'] if l is None)}/{len(a['events'])}"
+                    )
 
 
 if __name__ == "__main__":