remove generate-proxies postinstall hack, resolve pullfrog source via bundler config

the postinstall script referenced scripts/generate-proxies.ts which isn't
included in the published npm package, silently breaking every npx install.
replaced the proxy stub approach with turbopack resolveAlias and webpack
conditionNames so both bundlers resolve pullfrog imports to TypeScript
source directly — matching what tsc already does via customConditions.

also moves PR summary format from handleWebhook into modes.ts so the
summarize mode prompt includes it directly.

Made-with: Cursor

package.json

@@ -20,7 +20,6 @@
     "scratch": "node scratch.ts",
     "upDeps": "pnpm up --latest",
     "lock": "pnpm install --no-frozen-lockfile",
-    "postinstall": "node scripts/generate-proxies.ts",
     "prepare": "cd .. && husky action/.husky"
   },
   "devDependencies": {