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>

app/providers/protocol.py

@@ -44,20 +44,6 @@ class SentimentData:
     recommendation: str | None = None  # "buy" | "hold" | "avoid" — actionable LLM view
 
 
-@dataclass(frozen=True, slots=True)
-class FundamentalData:
-    """Fundamental metrics returned by fundamental providers."""
-
-    ticker: str
-    pe_ratio: float | None
-    revenue_growth: float | None
-    earnings_surprise: float | None
-    market_cap: float | None
-    fetched_at: datetime
-    next_earnings_date: date | None = None
-    unavailable_fields: dict[str, str] = field(default_factory=dict)
-
-
 # ---------------------------------------------------------------------------
 # Provider Protocols
 # ---------------------------------------------------------------------------
@@ -81,9 +67,5 @@ class SentimentProvider(Protocol):
         ...
 
 
-class FundamentalProvider(Protocol):
-    """Protocol for fundamental data providers."""
-
-    async def fetch_fundamentals(self, ticker: str) -> FundamentalData:
-        """Fetch fundamental data for a ticker."""
-        ...
+# No fundamentals provider protocol: since A6 fundamentals come only from the
+# batch SEC/Dolt imports, never from a request-time provider call.