style(cso): format lib/cso TypeScript with pinned Prettier

Mechanical reformat only. Minified transpile output is byte-identical for
21 of 22 files; witness.ts differs only in three regex flag orders
(/mi -> /im), which JavaScript canonicalizes. Source-text assertions over
lib/cso now compare whitespace-insensitively with the same tokens.

package.json

@@ -11,6 +11,8 @@
   "scripts": {
     "build": "bash scripts/build.sh",
     "build:cso": "bash scripts/build-cso.sh",
+    "format:cso": "prettier --write 'lib/cso/*.ts'",
+    "format:cso:check": "prettier --check 'lib/cso/*.ts'",
     "test:cso:docker": "bun test --max-concurrency 1 test/cso-docker-integration.test.ts test/cso-node-lifecycle-integration.test.ts test/cso-stack-cold-integration.test.ts",
     "test:cso:macos": "bun test test/cso-macos-launcher.test.ts test/cso-registry-socket.test.ts",
     "test:cso:windows": "bun test test/cso-windows-launcher.test.ts",
@@ -88,6 +90,7 @@
   "devDependencies": {
     "@anthropic-ai/claude-agent-sdk": "0.2.117",
     "@anthropic-ai/sdk": "^0.78.0",
+    "prettier": "3.9.9",
     "xterm": "^5.3.0",
     "xterm-addon-fit": "^0.8.0"
   },