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/_archive/security-assessments/M015-hostile-fixture-setup.md

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+# M015 Hostile Fixture Setup
+
+## Goal
+
+Produce a trustworthy local runtime for cross-user authorization probes.
+
+## Key discovery
+
+The default development SQLite database in `JobTrackerApi/jobtracker.db` is **not** a trustworthy authorization-test target:
+
+- it contains Identity and some later feature tables
+- it does **not** contain the core domain tables needed for real cross-user job/correspondence/attachment probing
+- current startup `Migrate()` behavior is therefore insufficient as the only hostile-test setup path
+
+## Chosen fixture strategy
+
+Use a dedicated clean SQLite fixture database created from the current EF model with `EnsureCreated()` semantics through a tiny helper program:
+
+- helper project: `tools/hostile-fixture-db/`
+- bootstrap script: `scripts/m015-hostile-fixture.sh`
+
+This keeps the hostile runtime inside repo code and the real API host while avoiding ad-hoc manual SQL.
+
+## What the helper does
+
+- creates a clean `jobtracker.db` under a caller-provided data root
+- builds the schema from the current `JobTrackerContext` model
+- verifies the presence of core tables needed for M015:
+  - `Companies`
+  - `JobApplications`
+  - `Correspondences`
+  - `Attachments`
+  - `RuleSettings`
+  - `AspNetUsers`
+
+## Runtime plan for S02
+
+1. Run `scripts/m015-hostile-fixture.sh`.
+2. Start the API with `Data__Root` pointing at that clean fixture root.
+3. Mint an admin dev token against the fixture DB.
+4. Create/reuse Alice and Bob through real API paths.
+5. Seed Alice-owned company/job/correspondence/attachment fixtures through the real API.
+6. Capture ids for cross-user hostile probes.
+
+## Honest boundary
+
+This slice establishes the trusted runtime path and fixture strategy. The full two-user seeded dataset and exploit execution belong in the next slice.