chore(claude): Restore always-on release guardrails

.claude/CLAUDE.md

@@ -47,6 +47,7 @@ Always loaded:
 | `.claude/rules/commit-guidelines.md` | Commit message format and prefixes |
 | `.claude/rules/pull-requests.md` | PR title and description conventions |
 | `.claude/rules/agent-instructions.md` | Delegation limits and implementation scope |
+| `.claude/rules/release.md` | Release guardrails — never hand-edit versions or tags |
 
 Loaded on demand, when a matching file is read (`paths:` frontmatter):
 

.claude/rules/release.md

@@ -0,0 +1,17 @@
+---
+description: Release guardrails — what never to do by hand. Full procedure is the /release skill.
+---
+
+# Release
+
+The procedure lives in the `/release` skill (invoke it deliberately; it does not auto-load).
+These constraints apply regardless of whether that skill was invoked.
+
+- **`release-prepare.yml` is the only sanctioned path** for bumping a version or creating a release
+  tag. Do not edit `version.properties` or `VERSION` by hand, and do not create `v*` tags manually —
+  `validate-tag` in `release-tag.yml` rejects anything not matching `v<M.m.p>-(rc|beta)N`.
+- **`tools/release/bump.sh` is the single source of truth for version logic.** Its versionCode
+  formula mirrors `buildSrc/src/main/java/ProjectConfig.kt` — the two must stay in sync.
+- CI runs `./tools/release/bump.sh --mode=check` on every PR (`check-release-tooling` in
+  `code-checks.yml`). If you did touch `version.properties` or `VERSION`, run that locally first.
+- All numeric version fields are bounded `0..99`; the versionCode formula collapses at ≥100.