docs: reorganize tree, restore architecture + research from archive, add Phase 0 reports

Active docs/ was stub scaffolding while the real docs sat in docs/_archive/.
Restore and correct them, and record the Phase 0 work.

- docs/architecture/current.md: verified system map (from archived SYSTEM_OVERVIEW,
  9 corrections against code).
- docs/research/competitors.md: sourced competitor analysis (from archived
  PRODUCT_RESEARCH, feature matrix corrected).
- docs/decisions/ADR-002-job-application-model.md: the Job/JobApplication split.
- docs/application-discovery-report.md, docs/implementation-roadmap.md,
  docs/phase-0-foundation-report.md, docs/career-workspace-branch-assessment.md.
- Remove 10 zero-byte placeholder files that advertised content that never existed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/security/two-factor-authentication.md

@@ -0,0 +1,82 @@
+# Two Factor Authentication
+
+## Purpose
+
+Provide additional account protection.
+
+---
+
+# Preferred Method
+
+TOTP authentication.
+
+Compatible with:
+
+- Google Authenticator.
+- Microsoft Authenticator.
+- Authy.
+
+---
+
+# Flow
+
+Enable 2FA:
+
+User requests setup
+
+↓
+
+Generate secret
+
+↓
+
+Display QR code
+
+↓
+
+User scans
+
+↓
+
+User confirms code
+
+↓
+
+Enable 2FA
+
+---
+
+# Login Flow
+
+Password/OAuth
+
+↓
+
+Request authenticator code
+
+↓
+
+Validate
+
+↓
+
+Login
+
+---
+
+# Recovery
+
+Support:
+
+- Backup codes.
+- Disable/reset through account recovery.
+
+---
+
+# UX Requirements
+
+Explain clearly:
+
+- Why enable 2FA.
+- How it works.
+- Recovery options.