improve(issue-list): fix PR #312 review concerns

- toNumericId: accept null, use Number.isInteger + n > 0 (was falsy-check)
- Remove fetchProjectId from resolveAllTargets/resolveOrgAndProject shared
  paths (dead code that added network calls to non-issue-list commands)
- Enrich env-var/config-default auto-detect targets in issue list using
  getProject directly with silent fallback to slug-based querying
- Fix test: spy on getProject in cursor-accepted test to avoid hitting
  the preload fetch mock (removed 3 [TEST] Unexpected fetch call warnings)

Author: BYK