chore: extract shared service methods into SQLiteStore (AC-480)

[jayscambler]

Summary

Added list_runs(), run_status(), and list_solved() service methods to SQLiteStore, then updated 4 consumers to delegate instead of duplicating raw SQL.

Problem

The same "list recent runs" SQL query was duplicated in 4 places:

• cli.py — list_runs command
• mcp/knowledge_tools.py — list_runs() tool
• server/cockpit_api.py — /api/runs endpoint
• server/app.py — WebSocket dashboard endpoint

Each had slightly different LIMIT values and column selections but identical intent.

Changes

New service methods on SQLiteStore

def list_runs(self, *, limit: int = 50) -> list[dict[str, Any]]
def run_status(self, run_id: str) -> list[dict[str, Any]]
def list_solved(self) -> list[dict[str, Any]]

Updated consumers

• cli.py: store.list_runs(limit=20) replaces raw SQL
• mcp/knowledge_tools.py: ctx.sqlite.list_runs(limit=20) replaces raw SQL
• server/app.py: store.list_runs(limit=50) and store.run_status(run_id) replace raw SQL
• server/cockpit_api.py: store.list_runs(limit=50) replaces raw SQL (enrichment loop kept)

TDD

Added test_service_layer.py with 7 tests covering empty, populated, and limit scenarios.

Verification

• ruff check src — all checks passed
• mypy src — zero errors
• pytest tests/ — all tests pass

Issue

Partially resolves AC-480

[linear]

AC-480 Extract shared service layer to deduplicate CLI/HTTP/MCP tool implementations