release: 0.7.6 (fix permission denied on global install)

The 0.7.5 tarball shipped `dist/bin/codegraph.js` without the executable
bit set, causing `zsh: permission denied: codegraph` after a fresh global
install. The build script now `chmod +x`'s the binary before packing.

Also adds CHANGELOG.md and documents the release workflow in CLAUDE.md.

CHANGELOG.md

@@ -0,0 +1,23 @@
+# Changelog
+
+All notable changes to CodeGraph are documented here. Each entry also ships as
+a [GitHub Release](https://github.com/colbymchenry/codegraph/releases) tagged
+`vX.Y.Z`, which is where most people will look.
+
+This project follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
+and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.7.6] - 2026-05-13
+
+### Fixed
+- `codegraph` CLI failing with `zsh: permission denied: codegraph` after a fresh
+  global install. The published 0.7.5 tarball shipped `dist/bin/codegraph.js`
+  without the executable bit, so the shell refused to run it through the npm
+  symlink. The build now `chmod +x`'s the binary before packing.
+
+  Already on 0.7.5? Either upgrade to 0.7.6, or unblock yourself in place:
+  ```bash
+  chmod +x "$(npm root -g)/@colbymchenry/codegraph/dist/bin/codegraph.js"
+  ```
+
+[0.7.6]: https://github.com/colbymchenry/codegraph/releases/tag/v0.7.6