feat(dolt): A2 — DoltHub earnings importer (shadow ingestion)

A SourceImporter that ingests post-no-preference/earnings into earnings_events
for the tracked universe. Shadow by construction (nothing reads earnings_events
until A4).

- earnings_alignment.py: pure calendar<->EPS-history min-cost monotonic DP,
  reused from scripts/import_dolthub_earnings.py with identical constants (not
  extending that one-off script); symbol/session normalization; unit-tested
  against the pinned constants.
- dolt_client.py: async dolt CLI wrapper (pull / current_commit / query_csv via
  asyncio.create_subprocess_exec — never blocks the shared event loop) + disk
  guard before pull.
- dolt_earnings_importer.py: detect_revision = pull + HEAD hash; stage = query
  earnings_calendar + eps_history, dedup, align, map act_symbol->ticker_id
  (normalize both sides so dotted BRK.B joins); promote is destructive
  (delete future dolt_earnings rows + upsert; past never deleted) so validate is
  FAIL-CLOSED — blocks when the staged forward calendar is empty or has collapsed
  below 50% of what's loaded (the forward calendar is the acceptance gate).
- NOTICE: CC BY-SA 4.0 attribution; config: DOLT_BINARY / DOLT_DATA_DIR / etc.

Verified end-to-end against the real 1.68 GB clone (5 tickers: 133 events, 128
paired, forward calendar to 2026-08-26, BRK.B joined). Tests: 9 alignment + 7
importer + 1 skip-guarded real-clone smoke. Full suite 699 passed.

Remaining for A2: wire the daily ~02:30 ET shadow cron — deferred to pair with
the deploy-time dolt install + DOLT_DATA_DIR provisioning.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.env.example

@@ -27,6 +27,17 @@ FINNHUB_API_KEY=
 # Fundamentals Provider — Alpha Vantage (optional fallback)
 ALPHA_VANTAGE_API_KEY=
 
+# Dolt bulk data — local clone of post-no-preference/earnings (workstream A).
+# DOLT_BINARY: path to the dolt CLI (set the full path in dev if it's not on PATH,
+#   e.g. Windows: C:\Program Files\Dolt\bin\dolt.exe). DOLT_DATA_DIR holds the
+#   clones; in PRODUCTION it MUST be outside the deploy tree (deploy is
+#   rsync --delete) — e.g. /var/lib/signal-platform/dolt. The earnings clone lives
+#   at <DOLT_DATA_DIR>/<DOLT_EARNINGS_SUBDIR>. Set up: dolt clone post-no-preference/earnings <dir>.
+DOLT_BINARY=dolt
+DOLT_DATA_DIR=dolt-data
+DOLT_EARNINGS_SUBDIR=earnings
+DOLT_MIN_FREE_DISK_GB=2.0
+
 # Regime Monitor — FRED (VIX + HY credit spreads). Free key: https://fred.stlouisfed.org/docs/api/api_key.html
 # Optional: without it the volatility (V1) and credit (C1) pillars show as n/a.
 FRED_API_KEY=