feat(ai): Add comprehensive pre-commit AI code review

Introduces a robust system for running automated, staged diff reviews against various large language models. This feature allows users to submit their changes to external AI services and receive structured feedback on potential bugs, security issues, and maintainability risks before committing.

The implementation covers the entire stack:
*   Backend logic was added to handle API communication with OpenAI, Anthropic, and custom endpoints.
*   A dedicated parser ensures that complex JSON outputs from LLMs are reliably converted into structured findings (severity, title, description).
*   New components and UI elements provide a clear visualization of the AI's assessment and actionable suggestions.

- Supports multiple major LLM providers (OpenAI, Anthropic)
- Parses structured JSON output for consistent review results
- Adds dedicated UI dialog to display AI findings and risk level

src/lib/types.ts

@@ -19,6 +19,24 @@ export interface CommitAiStatus {
   error: string | null;
 }
 
+export type AiReviewRisk = "low" | "medium" | "high";
+export type AiReviewSeverity = "critical" | "warning" | "info";
+
+export interface AiReviewFinding {
+  severity: AiReviewSeverity;
+  title: string;
+  description: string;
+  file: string | null;
+  line: number | null;
+  suggestion: string;
+}
+
+export interface AiReviewResult {
+  summary: string;
+  risk: AiReviewRisk;
+  findings: AiReviewFinding[];
+}
+
 export interface LocalModelOption {
   id: string;
   label: string;