fix(frontend): don't UserDraft.remove flows while route is still mounted

The /flows/add and /flows/edit routes drive FlowBuilder from a flowStore
whose getter reads flowHandle.draft directly. Calling UserDraft.remove
synchronously before goto() therefore wiped the in-memory entry, made
flowStore.val collapse to emptyFlow(), and tripped
UnsavedConfirmationModal against the just-saved value — even though the
deploy/save-draft itself succeeded.

Drop those explicit removes in onSaveInitial, /add onDeploy, and
/edit onDeploy. The empty-path entry self-cleans on unmount via
onDestroy ref counting; for the non-empty edit path the next visit's
load-time diff will silently overwrite localStorage when the local
autosave matches the deployed value. Restore-draft/restore-deployed
keep their explicit remove because they navigate to the same route
(no modal) and loadFlow immediately rehydrates the handle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/routes/(root)/(logged)/flows/add/+page.svelte

@@ -174,11 +174,9 @@
 
 <FlowBuilder
 	onSaveInitial={(e) => {
-		UserDraft.remove('flow', '')
 		goto(`/flows/edit/${e.path}?selected=${e.id}`)
 	}}
 	onDeploy={(e) => {
-		UserDraft.remove('flow', '')
 		goto(`/flows/get/${e.path}?workspace=${$workspaceStore}`)
 	}}
 	onDetails={(e) => {

frontend/src/routes/(root)/(logged)/flows/edit/[...path]/+page.svelte

@@ -270,7 +270,11 @@
 {:else}
 	<FlowBuilder
 		onDeploy={(e) => {
-			UserDraft.remove('flow', flowDraftPath)
+			// Don't UserDraft.remove here — the route's flowStore reads the
+			// handle's draft directly, so clearing it before goto would blank
+			// the flow value and trip UnsavedConfirmationModal. The entry's
+			// ref count drops on unmount and the next visit's load-time diff
+			// will silently overwrite localStorage with the deployed value.
 			goto(`/flows/get/${e.path}?workspace=${$workspaceStore}`)
 		}}
 		onDetails={(e) => {