feat: add semantic search tool for code symbol indexing and searching

- Implemented a new tool for semantic code search that indexes Rust code symbols (functions, structs, enums, traits, modules) and allows searching by name, concept, or meaning.
- Introduced a symbol index structure with methods for rebuilding the index and searching symbols.
- Added regex patterns for extracting various code symbols from Rust source files.
- Implemented scoring logic for search results based on exact matches, prefix matches, and context relevance.
- Created a web search tool that interacts with a SearXNG instance to fetch documentation and API information based on user queries.
- Added a diff preview overlay for rendering git diff output with color-coded additions and deletions in a TUI interface.

apps/interfaces/ws/src/lib.rs

@@ -92,6 +92,8 @@ async fn handle_socket(mut socket: WebSocket, state: Arc<WsState>) {
                                 api_key,
                                 model,
                                 api_base: None,
+                                edit_count: 0,
+                                consecutive_empty_reviews: 0,
                             };
 
                             zesdex_infrastructure::agent::spawn_agent_turn(params);