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/ai/privacy.md

@@ -0,0 +1,37 @@
+# AI Privacy
+
+## Principles
+
+Users control their data.
+
+---
+
+# External AI Providers
+
+Before sending data:
+
+Clearly communicate:
+
+- What is sent.
+- Why it is needed.
+- Provider used.
+
+---
+
+# Future SaaS
+
+Support:
+
+- User consent.
+- Data deletion.
+- Export.
+
+---
+
+# Sensitive Information
+
+Be careful with:
+
+- Personal details.
+- Employment history.
+- Documents.