chore: decommission FMP, Finnhub and Alpha Vantage (A6)

The A5 cutover has been on and observed in production, so SEC Company Facts +
DoltHub earnings are already the live source for `fundamental_data`. This
removes everything the legacy path still occupied.

Gone: the three providers and their config/env keys; the weekly
`fundamental_collector` job; the cutover toggle (SEC + Dolt is now the
unconditional path, so `off` can no longer silently freeze scoring inputs); the
A5 parity report, whose deltas became structurally zero once the candidate
builder started writing the table it compared against; and the FMP tier of
universe bootstrap.

Two behavioral notes:

- Disabling **SEC Fundamentals Import** now stops the SEC network fetch only.
  The local cache refresh moved outside the job-enable check, because candidates
  also derive from daily closes and earnings events — freezing those on an
  ingestion pause would stale scoring with no fallback left to recover from.
- `/ingestion/fetch?sources=fundamentals` still accepts the key and reports
  `skipped`; there is no per-ticker fetch any more.

Migration 029 does not blanket-delete the leftover settings rows. Migrations run
before the service restart, and pre-A6 code reads an absent `job_*_enabled` row
as *enabled* — so the two behavior-bearing keys become tombstones pinned to safe
values (hidden in Admin) and only the inert three are deleted. Removing the
provider keys from the production `.env` is the matching rollout step.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/extend_snapshot_universe.py

@@ -128,11 +128,10 @@ async def _resolve_pool() -> tuple[list[str], dict[str, str]]:
     """Return sorted unique symbols and source labels.
 
     Offline-safe: does **not** use production Postgres or SystemSetting cache
-    (those require a schema). Public sources first, then FMP, then seeds.
+    (those require a schema). Public sources first, then seeds.
     """
     from app.services.ticker_universe_service import (
         _SEED_UNIVERSES,
-        _fetch_universe_symbols_from_fmp,
         _fetch_universe_symbols_from_public,
         _normalise_symbols,
     )
@@ -150,19 +149,11 @@ async def _resolve_pool() -> tuple[list[str], dict[str, str]]:
         cleaned = _normalise_symbols(public_symbols)
         if cleaned:
             src = public_source or "public"
-        else:
-            if public_failures:
-                print(
-                    f"  WARNING: public fetch {universe}: "
-                    f"{'; '.join(public_failures[:3])}"
-                )
-            try:
-                fmp_symbols = await _fetch_universe_symbols_from_fmp(universe)
-                cleaned = _normalise_symbols(fmp_symbols)
-                if cleaned:
-                    src = "fmp"
-            except Exception as exc:
-                print(f"  WARNING: FMP fetch {universe}: {exc}")
+        elif public_failures:
+            print(
+                f"  WARNING: public fetch {universe}: "
+                f"{'; '.join(public_failures[:3])}"
+            )
 
         if not cleaned:
             cleaned = _normalise_symbols(_SEED_UNIVERSES.get(universe, []))