fix: show 'Installing search...' when qmd missing instead of 'Indexing...'

On fresh installs without qmd, show the accurate "Installing search..."
phase instead of briefly flashing "Indexing..." before switching to
unavailable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hooks/useIndexing.ts

@@ -66,7 +66,7 @@ export function useIndexing(vaultPath: string) {
         if (needsIndexing && !indexingRef.current) {
           indexingRef.current = true
           setProgress({
-            phase: 'scanning',
+            phase: status.qmd_installed ? 'scanning' : 'installing',
             current: 0,
             total: status.indexed_count,
             done: false,