feat(config): redo config tab — lazy list, full-coverage search, per-field reset (#898)

- LazyColumn + precomputed flat dot-path value map: O(1) lookups, only
  visible fields compose (829 live leaves on a real config)
- Search now matches keys, labels, descriptions, categories, CURRENT
  values and select options; non-schema ('Other') paths are searchable too.
  Result count + category chip per hit while searching
- Per-field reset-to-default icon; clear-to-blank honoring schema
  'clearable'; searchable dropdown honoring schema 'searchable'
  (select-all-free fresh filter, exact-match commits on blur)
- Number/object/list editors keep local text state: intermediate typing
  ('0.') no longer drops keystrokes; objects/lists edit as multi-line JSON
  with validation
- Honor backend searchable/clearable schema flags (SchemaField model)
- Category reset now previews default values immediately

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/model/Config.kt

@@ -26,6 +26,8 @@ data class SchemaField(
     val description: String? = null,
     val category: String? = null,
     val options: List<String>? = null,
+    val searchable: Boolean = false,
+    val clearable: Boolean = false,
 )
 
 @Serializable