refactor(types): move shared types from renderer to shared directory

- Move type definitions from src/renderer/src/types/ to src/shared/types/
- Add @shared/* path alias to tsconfig.node.json and tsconfig.web.json
- Update all imports from @renderer/types/* to @shared/types/*
- Update AGENTS.md with new directory structure and path alias

This fixes architecture violation where main/preload processes imported
from renderer directory. Types are now properly shared across all processes.

tsconfig.node.json

@@ -5,6 +5,7 @@
     "src/main/**/*",
     "src/preload/**/*",
     "src/renderer/**/*",
+    "src/shared/**/*"
   ],
   "compilerOptions": {
     "composite": true,
@@ -13,7 +14,8 @@
     "paths": {
       "@main/*": ["src/main/*"],
       "@preload/*": ["src/preload/*"],
-      "@renderer/*": ["src/renderer/src/*"]
+      "@renderer/*": ["src/renderer/src/*"],
+      "@shared/*": ["src/shared/*"]
     }
   }
 }