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/product/personas.md

@@ -0,0 +1,121 @@
+# User Personas
+
+---
+
+# Persona 1: Active Job Seeker
+
+## Description
+
+Someone actively searching and applying for roles.
+
+---
+
+## Problems
+
+- Losing track of applications.
+- Forgetting follow-ups.
+- Managing multiple CV versions.
+- Repeating information.
+
+---
+
+## Needs
+
+- Simple tracking.
+- Clear progress.
+- Better applications.
+- Organisation.
+
+---
+
+## Key Workflow
+
+Find job
+
+↓
+
+Add application
+
+↓
+
+Prepare documents
+
+↓
+
+Apply
+
+↓
+
+Track progress
+
+---
+
+# Persona 2: Career Changer
+
+## Description
+
+Someone moving into a new industry.
+
+---
+
+## Problems
+
+- Translating experience.
+- Knowing transferable skills.
+- Creating relevant CVs.
+
+---
+
+## Needs
+
+- Career profile.
+- AI suggestions.
+- Tailored documents.
+
+---
+
+# Persona 3: Graduate / Early Career
+
+## Description
+
+Someone entering employment.
+
+---
+
+## Problems
+
+- Limited experience.
+- Understanding expectations.
+- Building professional documents.
+
+---
+
+## Needs
+
+- Guidance.
+- Templates.
+- Structured workflows.
+
+---
+
+# Persona 4: Technical Professional
+
+## Description
+
+Experienced worker applying for specialised roles.
+
+---
+
+## Problems
+
+- Many applications.
+- Complex experience.
+- Multiple CV variants.
+
+---
+
+## Needs
+
+- Powerful customisation.
+- Automation.
+- Detailed tracking.