refactor: update git index refresh to a no-op and change logging level to debug

The `refresh_git_index` function is now a no-op, as the previous implementation added unnecessary latency without meaningful benefits. Additionally, logging levels for performance metrics have been changed from info to debug across various modules to reduce verbosity and improve performance during normal operations.

src/syncback/fs_snapshot.rs

@@ -291,7 +291,7 @@ impl FsSnapshot {
     ) -> io::Result<()> {
         let base_path = base.as_ref();
 
-        log::info!(
+        log::debug!(
             "[PERF] write_to_vfs_parallel: {} files, {} dirs to add; {} files, {} dirs to remove",
             self.added_files.len(),
             self.added_dirs.len(),
@@ -318,7 +318,7 @@ impl FsSnapshot {
                 };
             }
         } // Release lock before parallel phase
-        log::info!(
+        log::debug!(
             "[PERF]   phase1 create dirs: {:.3}s",
             phase1_timer.elapsed().as_secs_f64()
         );
@@ -369,7 +369,7 @@ impl FsSnapshot {
             }
         });
 
-        log::info!(
+        log::debug!(
             "[PERF]   phase2 write files: {:.3}s (git_skip={}, byte_skip={}, size_diff={})",
             phase2_timer.elapsed().as_secs_f64(),
             git_skipped.load(Ordering::Relaxed),
@@ -409,7 +409,7 @@ impl FsSnapshot {
             }
         });
 
-        log::info!(
+        log::debug!(
             "[PERF]   phase3 remove files: {:.3}s",
             phase3_timer.elapsed().as_secs_f64()
         );
@@ -446,7 +446,7 @@ impl FsSnapshot {
             }
         }
 
-        log::info!(
+        log::debug!(
             "[PERF]   phase4 remove dirs: {:.3}s",
             phase4_timer.elapsed().as_secs_f64()
         );

src/syncback/mod.rs

@@ -154,9 +154,9 @@ pub fn syncback_loop_with_stats(
 
     // Collect all instance paths BEFORE pruning so we can track external references
     // (references to instances that will be pruned, like SoundGroups in SoundService).
-    log::info!("[PERF] syncback_loop entered");
+    log::debug!("[PERF] syncback_loop entered");
     let pre_prune_paths = collect_all_paths(&new_tree);
-    log::info!(
+    log::debug!(
         "[PERF] collect_all_paths: {:.3}s",
         phase_timer.elapsed().as_secs_f64()
     );
@@ -195,7 +195,7 @@ pub fn syncback_loop_with_stats(
     if ignore_hidden {
         strip_hidden_services(&mut new_tree);
     }
-    log::info!(
+    log::debug!(
         "[PERF] prune + filter: {:.3}s",
         phase_timer.elapsed().as_secs_f64()
     );
@@ -203,7 +203,7 @@ pub fn syncback_loop_with_stats(
     let phase_timer = std::time::Instant::now();
     let mut deferred_referents = collect_referents(&new_tree, &pre_prune_paths, None);
     let placeholder_map = std::mem::take(&mut deferred_referents.placeholder_to_source_and_target);
-    log::info!(
+    log::debug!(
         "[PERF] collect_referents: {:.3}s",
         phase_timer.elapsed().as_secs_f64()
     );
@@ -262,7 +262,7 @@ pub fn syncback_loop_with_stats(
     if !ignore_referents {
         link_referents(deferred_referents, &mut new_tree)?;
     }
-    log::info!(
+    log::debug!(
         "[PERF] filter props + link refs: {:.3}s",
         phase_timer.elapsed().as_secs_f64()
     );
@@ -275,13 +275,13 @@ pub fn syncback_loop_with_stats(
             || hash_tree(project, old_tree.inner(), old_tree.get_root_id()),
             || hash_tree(project, &new_tree, new_tree.root_ref()),
         );
-        log::info!(
+        log::debug!(
             "[PERF] hash both trees (parallel): {:.3}s",
             phase_timer.elapsed().as_secs_f64()
         );
         result
     } else {
-        log::info!("[PERF] hash skipped (clean mode)");
+        log::debug!("[PERF] hash skipped (clean mode)");
         (HashMap::new(), HashMap::new())
     };
 
@@ -295,7 +295,7 @@ pub fn syncback_loop_with_stats(
                 .into_iter()
                 .filter(|p| is_valid_path(&ignore_patterns, project_path, p))
                 .collect();
-            log::info!(
+            log::debug!(
                 "[PERF] orphan scan: reusing pre-walked paths ({} -> {} after syncback filters)",
                 before,
                 filtered.len()
@@ -465,7 +465,7 @@ pub fn syncback_loop_with_stats(
     } else {
         HashSet::new()
     };
-    log::info!(
+    log::debug!(
         "[PERF] orphan scan: {:.3}s ({} paths)",
         phase_timer.elapsed().as_secs_f64(),
         existing_paths.len()
@@ -649,7 +649,7 @@ pub fn syncback_loop_with_stats(
 
         snapshots.extend(syncback.children);
     }
-    log::info!(
+    log::debug!(
         "[PERF] main walk loop: {:.3}s ({} instances, syncback={:.3}s, merge={:.3}s, path={:.3}s)",
         phase_timer.elapsed().as_secs_f64(),
         walk_count,
@@ -676,7 +676,7 @@ pub fn syncback_loop_with_stats(
             let relative = crate::compute_relative_ref_path(&source_abs, &target_abs);
             substitutions.push((placeholder.clone(), relative));
         }
-        log::info!(
+        log::debug!(
             "[PERF] build ref substitutions: {:.3}s (count={})",
             phase_timer.elapsed().as_secs_f64(),
             substitutions.len()
@@ -686,7 +686,7 @@ pub fn syncback_loop_with_stats(
         if !substitutions.is_empty() {
             fs_snapshot.fix_ref_paths(&substitutions);
         }
-        log::info!(
+        log::debug!(
             "[PERF] apply ref substitutions: {:.3}s",
             sub_timer.elapsed().as_secs_f64()
         );
@@ -917,7 +917,7 @@ pub fn syncback_loop_with_stats(
         }
     }
 
-    log::info!(
+    log::debug!(
         "[PERF] orphan removal: {:.3}s",
         phase_timer.elapsed().as_secs_f64()
     );