[0takuc0mrade]

Description

Fix four assigned backend issues affecting webhook delivery, historical analytics, and GraphQL account balances.

Type of Change

• Bug fix
• Test addition or update
• Documentation update

Related Issues

Closes #1694
Closes #1695
Closes #1696
Closes #1697

Changes Made

• Refresh the webhook timestamp and HMAC immediately before every HTTP attempt while retaining one logical delivery ID and unchanged payload.
• Count only completed production deliveries when evaluating failure streaks. Exclude test pings and pending retries before limiting the history; keep successful production deliveries as streak resets.
• Return historical averages as PostgreSQL NUMERIC strings, preserving the full fractional precision and scale without rounding. Document this behavior for hourly and daily responses.
• Aggregate account streams with one sender-or-recipient query so self-directed streams count once. Calculate claimable funds only from incoming streams using the shared accrual calculator, including paused/inactive handling and remaining-balance caps.

Testing

• Backend TypeScript build: cd backend && npm run build — passed.
• Full backend suite with an isolated PostgreSQL 16 database: npm test --workspace backend -- --maxWorkers=2 --reporter=dot — 78 files passed; 924 tests passed, 6 skipped. All configured coverage thresholds passed (75.71% statements, 81.02% branches, 74.41% functions).
• Ran the regression tests against the original upstream source: 14 failures reproduced across all four issues; restored the fixes before the passing full-suite run.
• Webhook coverage verifies all five attempts with fake time and the default 300-second signature tolerance, stable delivery IDs, HTTP/network terminal failures, ignored test/in-flight rows, and successful-delivery streak resets.
• HTTP coverage exercises integer-looking and fractional NUMERIC averages through both hourly and daily responses, plus outgoing-only, unvested incoming, self-directed, paused, inactive, capped, mixed, and empty GraphQL account totals.

Checklist

• Self-review completed
• Regression tests added and existing backend tests pass
• Backend build passes
• Precision behavior documented
• All four issues linked with closing keywords