feat(packaging): level-based source hub — Core + DevKit packaging, Platform/Enterprise scaffold

Organize CASAN as a reusable source hub with SPLIT releases so downstream adopts only the
level it needs (packaging/levels.json is the single source of truth).

Implemented now:
- Level 1 Core: bin/casan CLI (run/gate/test/verify/reuse/dashboard) + VERSION.
- Level 2 DevKit: packages/casan-devkit (install.sh, Dockerfile.harness, templates:
  project scaffold, domain-pack, gitea-workflow).
- scripts/package-release.sh core|devkit|platform|all-in-one-demo — builds split bundles
  into dist/ (BUNDLE-MANIFEST + SHA256SUMS); platform is stamped PREVIEW/INCOMPLETE;
  enterprise (future) is REFUSED (exit 3, no fake-complete package). Bundles verified:
  extract → bin/casan works, deterministic + domain suites pass, casan reuse VALID.
- docs/packaging: CASAN_PACKAGING_PLAN + ADOPTION + CI + DOMAIN_PACK + GITEA_PACKAGE + DOCKER.

Structure + docs only:
- Level 3 packages/casan-platform (dashboard exists; control-panel/viewers pending).
- Level 4 packages/casan-enterprise (RBAC/tenant/KMS/WORM/approval exist in core; governed
  console pending). No Chat Console/RBAC-console/tenant-console/model-mgmt built in this task.

Harness change (enables extracted bundles to self-resolve): casan-paths.sh + the Python
project_root() walk-ups now accept a second root marker `packages/casan-harness` in addition
to `.specify`, so a freshly-unpacked core/devkit/demo bundle (no `.specify` yet) roots
correctly and creates state on first run. In an adopted repo `.specify` still matches first.
policy-bundle.yaml paths corrected to packages/casan-harness (re-signed). Full gate 64/0/3.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/packaging/DOMAIN_PACK_GUIDE.md

@@ -0,0 +1,52 @@
+# CASAN Domain Pack Guide
+
+A **Domain Pack** is the per-project data the harness needs to govern YOUR domain. It lives
+at `apps/<project>/domain/` and is selected via `CASAN_DOMAIN_ROOT`. The harness code
+(`packages/casan-harness/`) never contains domain data — this is what makes it reusable.
+
+Scaffold template: `packages/casan-devkit/templates/domain-pack/`.
+
+## Layout
+```
+apps/<project>/domain/
+├── domain-pack.yaml           # manifest describing this pack
+├── input/
+│   ├── requirement.md         # FR-xx table drives the traceability gate
+│   └── architecture.md        # optional tech-stack/context
+├── golden-runs/
+│   └── <artifact>.golden.txt  # baseline for drift detection (H7)
+├── corpus/
+│   ├── redteam-corpus.jsonl   # attack vectors (H4 recall) — one JSON per line
+│   ├── redteam-vectors.jsonl  # vectors for benign-fp-report / redteam metrics
+│   └── benign-corpus/*.txt    # benign samples (H4 false-positive budget)
+└── traceability-map.json      # FR-xx → code files + test files (+ optional symbols/lines)
+```
+
+## Each piece
+- **input/requirement.md** — must contain a `| FR-xx | ... |` table. The traceability gate
+  (Plan-10) requires every `FR-xx` to map to ≥1 existing code file and ≥1 test file. No
+  secrets/PII (the H4 input scan blocks them).
+- **golden-runs/** — a canonical "good" artifact per pipeline output. `drift-detect` compares
+  a run against it; similarity 1.0 = no drift. Real drift detection is proven separately.
+- **corpus/** — red-team attack vectors (scored for H4 recall) + a benign corpus (bounds the
+  false-positive rate). Domain-specific injections make the H4 score meaningful.
+- **traceability-map.json** — `{"FR-01": {"name": "...", "code": ["backend/src/...", {"file":"...","symbols":["Foo"],"lines":[12]}], "tests": ["..."]}}`. Symbol/line refs are
+  optional but tighten the gate.
+- **domain-pack.yaml** — documents the above + optional threshold overrides.
+
+## Wire it up
+```bash
+export CASAN_DOMAIN_ROOT=apps/<project>/domain
+bin/casan gate                 # runs domain-dependent suites against your pack
+```
+`domain_root` is also recorded per-project in `packages/casan-harness/level5/project-registry.json`
+so `bin/casan reuse` can prove multi-project reuse.
+
+## Reference example
+The OKR app's own pack is the worked example: `apps/okr/domain/` (golden-runs, corpus,
+input, traceability-map). Copy its shape for your domain.
+
+## Toward Plan-12 (Domain Pack SDK)
+Today a pack is a directory + `CASAN_DOMAIN_ROOT`. Plan-12 will make it fully declarative
+(register a pack by manifest, no manual wiring). The `domain-pack.yaml` here is the seed of
+that manifest.