feat: Add Windows-compatible file locking for daemon

Replace Unix-only syscall.Flock with gofrs/flock library for
cross-platform file locking. This enables the daemon to run on
Windows in addition to Unix-like systems.

- Add github.com/gofrs/flock v0.13.0 dependency
- Replace syscall.Flock calls with flock.TryLock/Unlock
- Maintain same non-blocking exclusive lock semantics

(gt-5354h)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

go.mod

@@ -7,6 +7,8 @@ require (
 	github.com/charmbracelet/bubbles v0.21.0
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/lipgloss v1.1.0
+	github.com/go-rod/rod v0.116.2
+	github.com/gofrs/flock v0.13.0
 	github.com/google/uuid v1.6.0
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/term v0.38.0
@@ -34,5 +36,10 @@ require (
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	github.com/ysmood/fetchup v0.2.3 // indirect
+	github.com/ysmood/goob v0.4.0 // indirect
+	github.com/ysmood/got v0.40.0 // indirect
+	github.com/ysmood/gson v0.7.3 // indirect
+	github.com/ysmood/leakless v0.9.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
 )