feat(bisect): add guided Git bisect support

Add interactive Git bisect support to the Tauri backend and UI.
Introduce BisectState and BisectCommit types for structured state.
Expose Tauri commands to query, start, mark, and reset sessions.
Add parsers, unit tests, and a Bisect dialog with toolbar and App wiring.

- Backend: new Tauri commands, state types, and helpers to parse bisect.
- Frontend: Bisect dialog, toolbar entry, and App integration to control flow.

src/lib/types.ts

@@ -236,6 +236,24 @@ export interface GitCommit {
   has_note: boolean;
 }
 
+export interface BisectCommit {
+  hash: string;
+  short_hash: string;
+  summary: string;
+  author_name: string;
+  date: string;
+}
+
+export interface BisectState {
+  active: boolean;
+  finished: boolean;
+  current: BisectCommit | null;
+  culprit: BisectCommit | null;
+  remaining_revisions: number | null;
+  remaining_steps: number | null;
+  message: string;
+}
+
 export interface GitCommitFile {
   path: string;
   old_path: string | null;