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/research/overview.md

@@ -0,0 +1,74 @@
+# Product Research Overview
+
+## Purpose
+
+Document competitor research and product decisions.
+
+Research should guide:
+
+- UX decisions.
+- Feature priorities.
+- Architecture choices.
+- Product positioning.
+
+---
+
+# Important Rule
+
+Competitors should inspire ideas.
+
+Do not blindly copy.
+
+Jobjakt has a different purpose:
+
+A complete job application management platform.
+
+---
+
+# Research Areas
+
+## CV Builders
+
+Examples:
+
+- FlowCV.
+- Novoresume.
+- Reactive Resume.
+- ElegantCV.
+
+---
+
+## Job Platforms
+
+Examples:
+
+- LinkedIn.
+- Indeed.
+- Jobscan.
+- Teal.
+
+---
+
+## Productivity Tools
+
+Examples:
+
+- Notion.
+- Linear.
+- Modern SaaS dashboards.
+
+---
+
+# Goal
+
+Build a product that combines:
+
+Job tracking.
+
++
+
+Career management.
+
++
+
+AI assistance.