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/technical/troubleshooting.md

@@ -0,0 +1,32 @@
+# Troubleshooting
+
+## Purpose
+
+Provide debugging approach.
+
+---
+
+# General Process
+
+1. Reproduce issue.
+2. Check logs.
+3. Identify affected component.
+4. Make smallest safe fix.
+5. Verify.
+
+---
+
+# Production Issues
+
+Check:
+
+- Application logs.
+- Docker status.
+- Database.
+- External services.
+
+---
+
+# Never
+
+Do not randomly change production configuration without understanding the cause.