Fix lockstep versioning and improve documentation

- Sync all packages to version 0.7.7
- Rewrite sync-versions.js to handle ALL inter-package dependencies automatically
- Fix web-ui dependency on pi-ai (was 0.6.0, now 0.7.7)
- Move agent fix changelog entry to coding-agent CHANGELOG
- Remove redundant agent CHANGELOG.md
- Improve README.md with clearer lockstep versioning docs
- Add /changelog command to display full changelog in TUI (newest last)
- Fix changelog description (not a scrollable viewer, just displays in chat)
- Update CHANGELOG for 0.7.7 release

packages/proxy/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@mariozechner/pi-proxy",
-	"version": "0.7.5",
+	"version": "0.7.7",
 	"type": "module",
 	"description": "CORS and authentication proxy for pi-ai",
 	"main": "dist/index.js",