Persist segment text edits to database on Enter

- Add update_segment Tauri command (calls existing update_segment_text query)
- Wire onTextEdit handler from TranscriptEditor to invoke update_segment
- Edits are saved to SQLite immediately when user presses Enter

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/lib.rs

@@ -11,7 +11,7 @@ use commands::ai::{ai_chat, ai_configure, ai_list_providers};
 use commands::export::export_transcript;
 use commands::project::{
     create_project, delete_project, get_project, list_projects, load_project_transcript,
-    save_project_transcript,
+    save_project_transcript, update_segment,
 };
 use commands::settings::{load_settings, save_settings};
 use commands::system::{get_data_dir, llama_list_models, llama_start, llama_status, llama_stop};
@@ -40,6 +40,7 @@ pub fn run() {
             delete_project,
             save_project_transcript,
             load_project_transcript,
+            update_segment,
             transcribe_file,
             run_pipeline,
             download_diarize_model,