upgrade claude-agent-sdk to 0.2.133, drop bundled binary

Bumps @anthropic-ai/claude-agent-sdk from ^0.2.71 to ^0.2.133. The new SDK
hardens handleControlRequest against post-close transport writes (v0.2.94+),
which fixes the unhandledRejection that crashed the daemon when the SDK fired
a fire-and-forget control_request after we'd torn down the transport.

The SDK now ships per-platform Claude Code binaries via optionalDependencies
(~210 MB each). Paseo requires user-installed `claude` on PATH instead — same
posture as Codex/OpenCode:

- after-pack now prunes @anthropic-ai/claude-agent-sdk-* from the Electron
  bundle, matching the existing per-platform pruning for onnxruntime, sharp,
  and node-pty.
- claude-agent.ts gains resolveClaudeBinary() (mirrors resolveCodexBinary):
  throws with install instructions when `claude` is missing, instead of
  silently falling back to the bundled binary.
- isAvailable() now checks isCommandAvailable("claude") instead of always
  returning true.

packages/server/package.json

@@ -57,7 +57,7 @@
   },
   "dependencies": {
     "@agentclientprotocol/sdk": "^0.17.1",
-    "@anthropic-ai/claude-agent-sdk": "^0.2.11",
+    "@anthropic-ai/claude-agent-sdk": "^0.2.133",
     "@getpaseo/highlight": "0.1.70-beta.1",
     "@getpaseo/relay": "0.1.70-beta.1",
     "@isaacs/ttlcache": "^2.1.4",