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.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@colbymchenry/codegraph",
-  "version": "0.7.2",
+  "version": "0.7.6",
   "description": "Supercharge Claude Code with semantic code intelligence. 94% fewer tool calls • 77% faster exploration • 100% local.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
@@ -13,7 +13,7 @@
     "README.md"
   ],
   "scripts": {
-    "build": "tsc && npm run copy-assets",
+    "build": "tsc && npm run copy-assets && node -e \"require('fs').chmodSync('dist/bin/codegraph.js', 0o755)\"",
     "preuninstall": "node dist/bin/uninstall.js",
     "copy-assets": "node -e \"const fs=require('fs');fs.mkdirSync('dist/db',{recursive:true});fs.copyFileSync('src/db/schema.sql','dist/db/schema.sql');fs.mkdirSync('dist/extraction/wasm',{recursive:true});fs.readdirSync('src/extraction/wasm').filter(f=>f.endsWith('.wasm')).forEach(f=>fs.copyFileSync('src/extraction/wasm/'+f,'dist/extraction/wasm/'+f))\"",
     "dev": "tsc --watch",