feat(api): autoclosed DB sessions + fights selectinload + webhooks pagination

[Roddygithub]

Summary

• `get_session` now commits on successful yield and rolls back on exception (so DB writes from route handlers persist without explicit `db.commit()`).
• `GET /api/v1/fights` now eagerly loads `agents` + `skills` via `selectinload` (closes the list endpoint N+1).
• `GET /api/v1/webhooks` accepts `limit` (1-1000) + `offset` parameters for operator pagination.
• OpenAPI `schema.d.ts` regenerated to reflect the new query params.

Commits

1. `feat(api): auto-commit get_sessions on success, rollback on exception`
2. `feat(api): preload agents + skills on GET /fights (closes list N+1)`
3. `feat(api): add limit/offset pagination to GET /webhooks`
4. `chore(web): regen OpenAPI schema.d.ts for webhooks pagination`

Test plan

• `cd apps/api && uv run pytest tests/ -x -q`
• `cd web && pnpm typecheck`
• `cd web && pnpm generate:api` (drift gate)