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/authorization.md

@@ -0,0 +1,43 @@
+# Authorization
+
+## Purpose
+
+Control access to resources.
+
+---
+
+# User Isolation
+
+A user must only access:
+
+- Their jobs.
+- Their CV.
+- Their files.
+- Their emails.
+- Their settings.
+
+---
+
+# Admin Role
+
+Admins may access:
+
+- System settings.
+- Provider configuration.
+- Monitoring.
+
+---
+
+# API Rules
+
+Every protected endpoint must verify:
+
+1. User identity.
+2. User permission.
+3. Resource ownership.
+
+---
+
+# Never Trust Frontend
+
+The backend must enforce permissions.