Standardize daemon detection with tryDaemonLock probe (bd-wgu4)

- Extract lock checking to internal/lockfile package
- Add lock probe in RPC client before connection attempts
- Update daemon discovery to use lock probe
- Eliminates unnecessary connection attempts when socket missing

Closes bd-wgu4

Amp-Thread-ID: https://ampcode.com/threads/T-3b863f21-3af4-49d3-9214-477d904b80fe
Co-authored-by: Amp <amp@ampcode.com>

internal/lockfile/process_wasm.go

@@ -0,0 +1,9 @@
+//go:build js && wasm
+
+package lockfile
+
+// isProcessRunning checks if a process with the given PID is running
+// In WASM, this always returns false since we don't have process management
+func isProcessRunning(pid int) bool {
+	return false
+}