Fix file browser: use ~ as default path, support tilde expansion

- Default to ~ instead of hardcoded /home/user — envd resolves it
  to the actual home dir of the configured user
- Pass ~ and ~/... paths through to envd for server-side expansion
- Resolve actual absolute path from response entries for breadcrumbs
- Fall back to / if home dir is empty or doesn't exist
- Fix leftover label prop on admin templates CopyButton

frontend/src/routes/admin/templates/+page.svelte

@@ -419,7 +419,7 @@
 						<td class="px-4 py-3.5">
 							<div class="flex items-center gap-1.5">
 								<span class="font-mono text-meta text-[var(--color-text-primary)]">{tmpl.name}</span>
-								<CopyButton value={tmpl.name} label="Copied name" />
+								<CopyButton value={tmpl.name} />
 							</div>
 						</td>
 						<td class="px-4 py-3.5">