Activate private installation usage counts

[neonwatty]

Summary

• enable installation-level successful-feedback counting only in production
• synchronize the repository privacy policy with the disclosure already live at https://bugdrop.dev/privacy
• add configuration contracts that keep development and preview fail-closed and require disclosure

Safety

• counting runs only after GitHub confirms successful Issue creation
• counter failures remain asynchronous and cannot disrupt feedback delivery
• usage records contain only schema version, installation ID, and count
• repository identity, feedback content, and reporter data are not retained
• current installations are eligible prospectively; no historical per-installation backfill occurs

Verification

• npm run lint
• npm run format:check
• npm run typecheck
• npm test (102 files, 1,597 tests)
• focused activation/counter/retention suite (49 tests)
• Wrangler production dry run confirmed the production-only flag and required bindings
• git diff --check
• PR Review Toolkit: no high-confidence issues

The production policy was published and verified before this activation PR was opened.