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/overview.md

@@ -0,0 +1,72 @@
+# AI System Overview
+
+## Purpose
+
+AI enhances Jobjakt workflows.
+
+It helps users:
+
+- Create better applications.
+- Improve documents.
+- Understand opportunities.
+- Prepare for interviews.
+
+AI does not replace user decisions.
+
+---
+
+# AI Philosophy
+
+Jobjakt is not an AI chatbot.
+
+AI should appear where it provides clear value.
+
+Examples:
+
+Good:
+
+"Improve this CV bullet point"
+
+Good:
+
+"Tailor this CV for this job"
+
+Good:
+
+"Suggest interview questions"
+
+Bad:
+
+Empty chat window with no context.
+
+---
+
+# AI Sources
+
+AI can use:
+
+- Career Profile.
+- Master CV.
+- Job descriptions.
+- User-provided documents.
+- Application history.
+
+---
+
+# User Control
+
+AI output must:
+
+- Be visible.
+- Be editable.
+- Require approval before saving.
+
+---
+
+# Important Rule
+
+Never silently modify:
+
+- Career profile.
+- Master CV.
+- Application documents.