chore: cargo fmt + clippy --fix sweep across the crate

Pure mechanical cleanup of accumulated drift in files outside the
HLS-content-hash branch's main change set. No behavior change.

- `cargo fmt` on every previously-misformatted file
  (`ai/insight_generator.rs`, `database/knowledge_dao.rs`,
  `faces.rs`, `knowledge.rs`, `libraries.rs`).
- `cargo clippy --fix`:
  - `needless_borrow`: `&library` → `library` in `handlers/image.rs`
    (two sites in the photo-listing path).
- Manual clippy pass for warnings clippy emits but can't auto-apply:
  - `field_reassign_with_default` in `database/reconcile.rs::run` —
    consolidated into a struct-literal initializer.
  - `needless_range_loop` in `database/knowledge_dao.rs::union_perceptual_tags`
    — inner `for b in (a+1)..indices.len() { let ib = indices[b]; ... }`
    becomes `for &ib in &indices[a + 1..] { ... }`.
  - Doc-list indentation: continuation lines under nested bullets in
    `database/mod.rs::get_memories_in_window` and
    `database/knowledge_dao.rs::build_entity_graph` realigned to the
    list-item content column.

Deliberately not touched (each deserves its own focused commit, with
testing, rather than getting bundled into a sweep):
- 4× `deprecated count_distinct` in `faces.rs` — diesel API migration
  to `AggregateExpressionMethods::aggregate_distinct` may shift result
  types; needs verification against the existing stats queries.
- `await_holding_lock` in `knowledge.rs:807` — `std::sync::Mutex` held
  across `ollama.generate(...).await`. Genuine concurrency bug; fix
  requires understanding the surrounding flow before just dropping
  the guard.
- 2× `type_complexity` in `database/mod.rs` — cosmetic, would need a
  `type` alias and corresponding callers updated.
- Dead `total_deleted` on `library_maintenance::GcStats` and
  `file_scan::enumerate_indexable_files` — both are public surface
  retained for future use; deletion is a separate decision.

All 707 tests still pass. Release build clean.

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

src/libraries.rs

@@ -94,7 +94,7 @@ pub fn parse_excluded_dirs_column(raw: Option<&str>) -> Vec<String> {
     match raw {
         None => Vec::new(),
         Some(s) => s
-            .split(|c: char| matches!(c, ',' | '\n' | '\r'))
+            .split([',', '\n', '\r'])
             .map(str::trim)
             .filter(|s| !s.is_empty())
             .map(String::from)
@@ -148,10 +148,7 @@ pub fn validate_excluded_dirs_entry(entry: &str) -> Result<String, String> {
     if let Some(rel) = trimmed.strip_prefix('/') {
         // Path form. Reject `..` traversal — `base.join(\"../x\")` doesn't
         // canonicalise, so `path.starts_with(...)` never matches.
-        if rel
-            .split('/')
-            .any(|seg| seg == "..")
-        {
+        if rel.split('/').any(|seg| seg == "..") {
             return Err(format!(
                 "'{}': '..' segments don't normalise — the prefix-match never fires",
                 trimmed
@@ -542,7 +539,10 @@ pub async fn patch_library(
         {
             Ok(n) => affected = affected.max(n),
             Err(e) => {
-                warn!("PATCH /libraries/{}: enabled update failed: {:?}", lib_id, e);
+                warn!(
+                    "PATCH /libraries/{}: enabled update failed: {:?}",
+                    lib_id, e
+                );
                 return HttpResponse::InternalServerError().body(format!("{}", e));
             }
         }
@@ -600,7 +600,9 @@ pub async fn patch_library(
             );
             HttpResponse::Ok().json(lib)
         }
-        None => HttpResponse::NotFound().body(format!("library id {} not found after update", lib_id)),
+        None => {
+            HttpResponse::NotFound().body(format!("library id {} not found after update", lib_id))
+        }
     }
 }
 
@@ -930,10 +932,7 @@ mod tests {
 
     #[test]
     fn validate_strips_trailing_slash_on_path_entries() {
-        assert_eq!(
-            validate_excluded_dirs_entry("/photos/").unwrap(),
-            "/photos"
-        );
+        assert_eq!(validate_excluded_dirs_entry("/photos/").unwrap(), "/photos");
         assert_eq!(
             validate_excluded_dirs_entry("/photos//").unwrap(),
             "/photos"