chore(governance): commit main branch protection ruleset + document policy

GitHub repository rulesets are gated by plan tier: free for public repos
and for paid private repos, blocked on the free plan + private. Until
the repo flips public (or the org upgrades), the rules below are
documented and enforced socially. Once the gate lifts, applying them
takes one command:

  gh api -X POST /repos/ai-driven-dev/aidd-framework/rulesets \
    --input .github/rulesets/main.json

Rules:
- direct push, force-push, and deletion of main forbidden
- pull request required, with at least one approving review and
  unresolved threads blocking merge
- required status checks: 'lefthook (framework-local checks)' from
  validate.yml + 'Commitlint' from ci.yml

The validate workflow runs every framework-local lefthook hook
(json-validity + schema validation, yaml-validity, skill-frontmatter,
evals-validity, summarize-plugin-catalogs) against the full tree, so
this single check is sufficient to gate the doc / config integrity
surface.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: blafourcade

.github/rulesets/main.json

@@ -0,0 +1,35 @@
+{
+  "name": "main protection",
+  "target": "branch",
+  "enforcement": "active",
+  "conditions": {
+    "ref_name": {
+      "include": ["refs/heads/main"],
+      "exclude": []
+    }
+  },
+  "rules": [
+    {
+      "type": "pull_request",
+      "parameters": {
+        "required_approving_review_count": 1,
+        "dismiss_stale_reviews_on_push": false,
+        "require_code_owner_review": true,
+        "require_last_push_approval": false,
+        "required_review_thread_resolution": true
+      }
+    },
+    {
+      "type": "required_status_checks",
+      "parameters": {
+        "strict_required_status_checks_policy": false,
+        "required_status_checks": [
+          {"context": "lefthook (framework-local checks)"},
+          {"context": "Commitlint"}
+        ]
+      }
+    },
+    {"type": "non_fast_forward"},
+    {"type": "deletion"}
+  ]
+}

GOVERNANCE.md

@@ -47,6 +47,23 @@ Prompt-only changes that alter how a skill behaves without changing its name or
 
 A maintainer or plugin owner with a direct stake in a PR (e.g. their employer or a paid integration) should disclose it in the PR description and abstain from being the sole approver. The lazy-consensus window stays the same, but a second maintainer approval becomes mandatory.
 
+## Branch protection on `main`
+
+Direct pushes to `main` are forbidden; every change lands through a pull request that satisfies the rules below. The machine-readable form lives at [`.github/rulesets/main.json`](.github/rulesets/main.json) and can be applied with:
+
+```
+gh api -X POST /repos/ai-driven-dev/aidd-framework/rulesets --input .github/rulesets/main.json
+```
+
+Rules:
+
+- **Pull request required.** No direct push to `main`, no force-push, no deletion.
+- **At least one approving review** from a maintainer (CODEOWNERS-aware).
+- **Required status checks**: `lefthook (framework-local checks)` (the [`validate`](.github/workflows/validate.yml) workflow) and `Commitlint` (from the [`CI`](.github/workflows/ci.yml) workflow) must pass.
+- **Unresolved review threads block merge.**
+
+The ruleset depends on GitHub's repository-rulesets API, which is free on public repos and bundled with paid plans on private repos. While the repo is private and on the free plan the rules are documented but not enforced by GitHub; they are enforced socially by maintainers.
+
 ## Code of Conduct
 
 All decisions and interactions are bound by the [Code of Conduct](./CODE_OF_CONDUCT.md). Enforcement contacts are listed there.