refactor(storage): extract WebhookRepository across all three storage adapters

[amitkojha05]

Summary

Implements the first step of the TODO on postgres.adapter.ts line 49:
Extracts all webhook and delivery methods from PostgresAdapter, SqliteAdapter, and MemoryAdapter into dedicated repository classes under apps/api/src/storage/adapters/repositories/. Each adapter becomes a thin facade that delegates to its repository. Follows the same pattern established in PR #13 (MultiConnectionPoller base class extraction).

Changes

• repositories/webhook.postgres.repository.ts — new, owns all Postgres webhook/delivery SQL
• repositories/webhook.sqlite.repository.ts — new, owns all SQLite webhook/delivery SQL
• repositories/webhook.memory.repository.ts — new, owns all in-memory webhook/delivery logic
• postgres.adapter.ts — delegates to WebhookPostgresRepository, retains if (!this.pool) guards
• sqlite.adapter.ts — delegates to WebhookSqliteRepository, retains if (!this.db) guards
• memory.adapter.ts — delegates to WebhookMemoryRepository, Maps moved into repository

Zero behavior changes. All three adapters implement the same StoragePort interface contract as before.

The updated TODO now lists the remaining domains to extract:

Checklist

• Unit / integration tests added — existing webhook-storage test suite covers all three adapters via the StoragePort interface; zero test changes required
• Docs added / updated — no user-facing docs affected by this refactor
• Roborev review passed — (internal)
• Competitive analysis done / discussed — (internal)
• Blog post about it discussed — (internal)

[github-actions]

All contributors have signed the CLA. ✅
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[amitkojha05]

I have read the CLA Document and I hereby sign the CLA

[amitkojha05]

@KIvanow @jamby77 Please review this PR ,would love to hear your feedback.

[KIvanow]

Looks good overall!