refactor: simplify compile.ts to single-target and add per-platform compile scripts

- Rewrite compile.ts from 112 to 66 lines: single target with auto-detect host, remove multi-target batch logic
- Add compile:linux/mac/win scripts to server, root, and turbo configs
- Wire desktop dist:* to depend on matching server compile:* (avoid unnecessary cross-platform compilation)
- Update AGENTS.md docs across root, server, and desktop

apps/server/package.json

@@ -6,6 +6,9 @@
   "scripts": {
     "build": "vite build",
     "compile": "bun compile.ts",
+    "compile:linux": "bun compile.ts --target bun-linux-x64",
+    "compile:mac": "bun compile.ts --target bun-darwin-arm64",
+    "compile:win": "bun compile.ts --target bun-windows-x64",
     "db:generate": "drizzle-kit generate",
     "db:migrate": "drizzle-kit migrate",
     "db:push": "drizzle-kit push",