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/03-design-principles.md

@@ -0,0 +1,113 @@
+# Design Principles
+
+## Goal
+
+Create a premium, modern career management experience.
+
+---
+
+# Visual Direction
+
+The application should feel:
+
+- Professional.
+- Modern.
+- Calm.
+- Intelligent.
+- Trustworthy.
+
+---
+
+# Inspirations
+
+## Notion
+
+For:
+
+- Organisation.
+- Clean interfaces.
+- Flexible content.
+
+## Linear
+
+For:
+
+- Professional software feel.
+- Speed.
+- Keyboard-friendly workflows.
+
+## FlowCV
+
+For:
+
+- CV creation experience.
+- Template selection.
+- Visual editing.
+
+## Jobscan
+
+For:
+
+- Career optimisation.
+
+---
+
+# Navigation
+
+Users should always understand:
+
+Where am I?
+
+What can I do?
+
+What happens next?
+
+---
+
+# Forms
+
+Forms should:
+
+- Be grouped logically.
+- Explain fields.
+- Validate clearly.
+- Avoid unnecessary questions.
+
+---
+
+# Empty States
+
+Every empty state should explain:
+
+- Why it matters.
+- What action to take.
+- How to get started.
+
+---
+
+# Errors
+
+Errors should:
+
+- Explain what happened.
+- Suggest next steps.
+- Avoid technical language.
+
+---
+
+# Dark Mode
+
+Dark mode should be supported.
+
+It should feel designed, not inverted.
+
+---
+
+# Accessibility
+
+All features should consider:
+
+- Keyboard navigation.
+- Screen readers.
+- Contrast.
+- Clear focus states.