feat(campaigns): wire up CampaignRunner + Sqlite/Parquet stores (M4)

[vcaries]

M4 — Campaigns layer

What

• hash_airfoil: stable 16-char SHA-1 over coordinates
• SqliteResultStore: DB-backed, idempotent on
  (airfoil_hash, alpha, Re, Mach, n_crit) PRIMARY KEY
• ParquetResultStore: in-memory buffer + flush to disk
• CampaignRunner: serial path (with convergence pipeline + store
  consultation) and parallel path via multiprocessing.Pool (parent
  owns the store to avoid pickling connections)
• CampaignResult value object with success_rate

Resumability

End-to-end test demonstrates: kill mid-run, relaunch against the same
store, solver.calls == 0 because every point is cached.

Tests

+17 unit tests (now 134 total). All green:

• ruff / ruff format / mypy / pytest ✅

Out of scope (next)

• M5: matplotlib plots + GIF/MP4 animation pipeline (the portfolio payoff)