fix(editors): use savedPath (deployed) as the pen-popover rename baseline

The topbar pen-popover path editor (EditorHeader, shared by flow/script/app/
raw-app) used `snapshotPath ?? path` as the Path widget's `initialPath`.
`snapshotPath` is the path captured when the popover opens (the *renamed* value
for a reopened rename draft) and exists only to freeze the breadcrumb while the
popover is open — it's the wrong rename baseline. Reverting a renamed draft to
its original path in the popover then tripped "path already used" (typed !=
stale baseline → existence check on the deployed path → match).

Use `savedPath` (the deployed/original path every caller already passes) as the
baseline instead; `snapshotPath` still drives the breadcrumb display only. New
items keep their reset-seeding behavior (savedPath is '' for them).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/EditorHeader.svelte

@@ -201,7 +201,7 @@
 							<Path
 								autofocus
 								bind:path
-								initialPath={snapshotPath ?? path ?? ''}
+								initialPath={savedPath ?? path ?? ''}
 								namePlaceholder={kind}
 								{kind}
 								size="sm"