[Bugfix #664] Read issue number from DB, not builder name

[waleedkadous]

Fixes #664

Root Cause

The dashboard's Issue column extracted issue numbers by regex-matching builder names against known protocol prefixes (spir-NNN, aspir-NNN, bugfix-NNN, etc.). Unknown protocols like research didn't match, so their issue number showed as the full builder name.

Fix

In getOverview(), after discovering builders from the filesystem, enrich issueId from the DB's issue_number column. The builders table already stores this value at spawn time. This is protocol-agnostic — works for any current or future protocol without regex updates.

Falls back gracefully to the regex-parsed value when the DB is unavailable (e.g., no Tower running).

Test Plan

• Added regression test: unknown protocol (research-533-*) gets correct issueId from DB
• Added test: DB value overrides regex-parsed value for known protocols
• Added test: falls back to regex when DB has no issue_number
• All 129 existing overview tests pass
• Full build succeeds
• Full test suite passes (excluding known flaky E2E tests)