Add missing --timeout flag to helmfile sync command with documentation (#2148)

* Initial plan

* Implement --timeout flag for helmfile sync command

- Add Timeout field to SyncOptions struct in pkg/config/sync.go
- Add --timeout flag to sync command in cmd/sync.go
- Add Timeout field to SyncOpts struct in pkg/state/state.go
- Modify timeoutFlags() function to prioritize CLI timeout over release and default configs
- Add test case to verify CLI timeout overrides other timeout settings
- Follow same pattern as existing --wait and --wait-for-jobs flags

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

* Fix lint issues: format test struct fields properly

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

* Update docs: Add --timeout flag documentation for helmfile sync command

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

pkg/config/sync.go

@@ -24,6 +24,8 @@ type SyncOptions struct {
 	WaitRetries int
 	// WaitForJobs is the wait for jobs flag
 	WaitForJobs bool
+	// Timeout is the timeout flag in seconds
+	Timeout int
 	// ReuseValues is true if the helm command should reuse the values
 	ReuseValues bool
 	// ResetValues is true if helm command should reset values to charts' default
@@ -124,6 +126,11 @@ func (t *SyncImpl) WaitForJobs() bool {
 	return t.SyncOptions.WaitForJobs
 }
 
+// Timeout returns the timeout
+func (t *SyncImpl) Timeout() int {
+	return t.SyncOptions.Timeout
+}
+
 // ReuseValues returns the ReuseValues.
 func (t *SyncImpl) ReuseValues() bool {
 	if !t.ResetValues() {