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>

tests/unit/test_ticker_universe_service.py

@@ -10,7 +10,6 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 from app.database import Base
-from app.exceptions import ProviderError
 from app.models.settings import SystemSetting
 from app.models.ticker import Ticker
 from app.services import ticker_universe_service
@@ -97,11 +96,7 @@ async def test_fetch_universe_symbols_uses_cached_snapshot_when_live_sources_fai
     async def _fake_public(_universe: str):
         return [], ["public failed"], None
 
-    async def _fake_fmp(_universe: str):
-        raise ProviderError("fmp failed")
-
     monkeypatch.setattr(ticker_universe_service, "_fetch_universe_symbols_from_public", _fake_public)
-    monkeypatch.setattr(ticker_universe_service, "_fetch_universe_symbols_from_fmp", _fake_fmp)
 
     symbols, source = await ticker_universe_service.fetch_universe_symbols(session, "sp500")
     assert symbols == ["AAPL", "MSFT"]
@@ -116,11 +111,7 @@ async def test_fetch_universe_symbols_uses_seed_when_live_and_cache_fail(
     async def _fake_public(_universe: str):
         return [], ["public failed"], None
 
-    async def _fake_fmp(_universe: str):
-        raise ProviderError("fmp failed")
-
     monkeypatch.setattr(ticker_universe_service, "_fetch_universe_symbols_from_public", _fake_public)
-    monkeypatch.setattr(ticker_universe_service, "_fetch_universe_symbols_from_fmp", _fake_fmp)
 
     symbols, source = await ticker_universe_service.fetch_universe_symbols(session, "sp500")
     assert "AAPL" in symbols