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/agent/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@mariozechner/pi-agent",
-	"version": "0.7.5",
+	"version": "0.7.7",
 	"description": "General-purpose agent with transport abstraction, state management, and attachment support",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -18,8 +18,8 @@
 		"prepublishOnly": "npm run clean && npm run build"
 	},
 	"dependencies": {
-		"@mariozechner/pi-ai": "^0.7.5",
-		"@mariozechner/pi-tui": "^0.7.5"
+		"@mariozechner/pi-ai": "^0.7.7",
+		"@mariozechner/pi-tui": "^0.7.7"
 	},
 	"keywords": [
 		"ai",