chore: bootstrap repo scaffolding (M0.1)

Adds the §1.2 scaffolding required by IMPLEMENTATION_PLAN.md M0.1:
README, CONTRIBUTING, CODEOWNERS, CHANGELOG, PR + issue templates,
CI workflow, release workflow, LICENSE, commitlint, cliff config,
.editorconfig, .gitignore, .env.example.

Refs: M0.1

commitlint.config.cjs

@@ -0,0 +1,32 @@
+// commitlint.config.cjs — Conventional Commits enforcement for every repo.
+// Used by .gitea/workflows/ci-*.yaml `wagoid/commitlint-github-action`.
+
+module.exports = {
+  extends: ['@commitlint/config-conventional'],
+  rules: {
+    'type-enum': [2, 'always', [
+      'feat',     // new feature
+      'fix',      // bug fix
+      'docs',     // documentation
+      'chore',    // tooling, deps, no production code change
+      'refactor', // refactor with no behavior change
+      'test',     // tests only
+      'perf',     // performance
+      'build',    // build system, Dockerfile
+      'ci',       // CI config
+      'revert',   // revert a prior commit
+    ]],
+    'subject-case': [2, 'always', 'sentence-case'],
+    'subject-max-length': [2, 'always', 72],
+    'body-max-line-length': [1, 'always', 100],
+    'footer-leading-blank': [2, 'always'],
+    'references-empty': [1, 'never'], // warn if no Refs: M1.2 footer
+  },
+  parserPreset: {
+    parserOpts: {
+      // Capture milestone references: "Refs: M5.2" or "Closes: M5.2"
+      referenceActions: ['close', 'closes', 'closed', 'fix', 'fixes', 'fixed', 'refs', 'ref'],
+      issuePrefixes: ['M', '#'],
+    },
+  },
+};