fix: relocate daemon socket for deep paths (GH#1001)

On Unix systems, socket paths are limited to 104 chars (macOS) or 108 chars
(Linux). Deep workspace paths like /Volumes/External Drive/Dropbox/...
would exceed this limit and cause daemon startup failures.

This fix:
- Adds ShortSocketPath() which computes /tmp/beads-{hash}/bd.sock for
  paths that would exceed the limit
- Keeps backward compatibility: short paths still use .beads/bd.sock
- Updates daemon discovery to check both locations
- Uses SHA256 hash of canonical workspace path for unique directories

Closes GH#1001

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/rpc/socket_path_windows.go

@@ -0,0 +1,35 @@
+//go:build windows
+
+package rpc
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// MaxUnixSocketPath is not applicable on Windows (uses TCP).
+// Kept for API compatibility.
+const MaxUnixSocketPath = 103
+
+// ShortSocketPath returns the socket path for Windows.
+// Windows uses TCP instead of Unix sockets, so path length is not a concern.
+// The "socket path" is actually a file containing the TCP endpoint info.
+func ShortSocketPath(workspacePath string) string {
+	return filepath.Join(workspacePath, ".beads", "bd.sock")
+}
+
+// EnsureSocketDir is a no-op on Windows since the .beads directory
+// should already exist.
+func EnsureSocketDir(socketPath string) (string, error) {
+	return socketPath, nil
+}
+
+// CleanupSocketDir removes the socket file on Windows.
+func CleanupSocketDir(socketPath string) error {
+	return os.Remove(socketPath)
+}
+
+// NeedsShortPath always returns false on Windows since TCP is used.
+func NeedsShortPath(workspacePath string) bool {
+	return false
+}