feat: implement contributor progression automation, Founding 1,000 cohort engine, and PR sync (Phase 5 & 6)

[ashishsinghbora]

Summary of Changes

• Automated Contributor Progression & Credential Pipeline (src/lib/progression/pipeline.ts):

  • Automatically evaluates objective advancement metrics upon pull request merges (Explorer → Contributor on 1st PR; Contributor → Active Contributor on 3 PRs; Active → Core Contributor on 10 PRs + 3 reviews + 2 projects).
  • Automatically mints cryptographic proof-of-work credentials (first_pr_merged, verified_contributor, core_contributor).
  • Records full audit trail in audit_logs (user.promoted, credential.issued).

• Founding 1,000 Allocation Engine (src/lib/founding/index.ts):

  • Strictly enforces the rule: Registration alone never awards a founding number.
  • Assigns sequential permanent numbers (1 to 1000) only upon verified merge of the contributor's first legitimate pull request.
  • Automatically mints the founding_1000 verifiable credential and updates the user profile and founding members registry.

• GitHub PR Synchronization Engine & Endpoint (src/lib/github/contributions.ts & POST /api/sync/contributions):

  • Scans official TechNexusOrg repositories for merged pull requests authored by the authenticated user.
  • Syncs any missing contributions and executes progression/credential evaluation without requiring dropped webhooks to block contributors.

• Dashboard & Campaign UI Enhancements:

  • Added ProgressionPath component with visual milestone progression stepper and requirements checklist.
  • Added SyncContributionsButton with live scan feedback.
  • Displays permanent Founding Member badge (#0042 Founding 1,000) on Dashboard header.
  • Display live recent #FirstPR graduates on /first-pr with real GitHub PR links and contributor passport links.

• Testing & Verification:

  • Added src/lib/founding/index.test.ts (sequential member allocation, deduplication, capacity checks).
  • Added src/lib/progression/pipeline.test.ts (first PR, multi-PR milestones, credential minting, audit logs).
  • Full suite passed: 13/13 test files (36/36 tests), 0 lint errors, 0 type errors, 15/15 routes built.