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/jobs-ai.md

@@ -0,0 +1,48 @@
+# Job AI Features
+
+## Purpose
+
+Help users understand opportunities.
+
+---
+
+# Features
+
+## Job Analysis
+
+Extract:
+
+- Required skills.
+- Responsibilities.
+- Seniority.
+- Keywords.
+
+---
+
+## Matching
+
+Compare:
+
+Job
+
+against
+
+Career Profile
+
+---
+
+Output:
+
+- Strengths.
+- Gaps.
+- Suggestions.
+
+---
+
+## Application Assistance
+
+Suggest:
+
+- CV improvements.
+- Cover letter topics.
+- Interview preparation.