Add shared types and client core packages

The wire contract every client codes against, plus the annotation engine,
canvas renderer and connection policy shared by both clients.

Claude-Session: https://claude.ai/code/session_01SS9F92jb51bMCRCKem6QtD

packages/shared-types/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "declaration": true,
+    "noEmit": true,
+    "skipLibCheck": true,
+    "verbatimModuleSyntax": true
+  },
+  "include": ["src/**/*.ts"]
+}