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_SESSION_START.md

@@ -0,0 +1,90 @@
+# AI Session Start Instructions
+
+Before making changes:
+
+1. Read:
+
+docs/MASTER_IMPLEMENTATION_GUIDE.md
+
+2. Read relevant documentation:
+
+docs/product/
+docs/architecture/
+docs/security/
+docs/technical/
+
+
+3. Review:
+
+- Current git status.
+- Recent changes.
+- Existing implementation.
+
+---
+
+# Working Rules
+
+You are working on an existing production application.
+
+Do not:
+
+- Rewrite without justification.
+- Remove working features.
+- Change architecture without understanding impact.
+- Assume documentation is correct over code.
+
+---
+
+# Before Coding
+
+Explain:
+
+- What you found.
+- What needs changing.
+- Why.
+
+For larger changes:
+
+Create an implementation plan.
+
+---
+
+# During Coding
+
+Prefer:
+
+- Small commits.
+- Clean abstractions.
+- Tests.
+- Documentation updates.
+
+---
+
+# Continue Working
+
+Do not stop after every small task.
+
+Continue with related improvements.
+
+Only ask for input when:
+
+- A decision cannot reasonably be inferred.
+- Multiple options have significant consequences.
+- Credentials/access are required.
+- A destructive choice is required.
+
+---
+
+# After Work
+
+Update:
+
+docs/CHANGELOG_AI_WORK.md
+
+Include:
+
+- Summary.
+- Files changed.
+- Tests.
+- Decisions.
+- Next steps.