feat: initial implementation of AI Commit Ext VS Code extension

- Add VS Code extension with OpenCode AI integration
- Generate Conventional Commit messages via SCM header button
- Include gitService for staged changes detection
- Include opencodeService for CLI invocation
- Add configuration options for model, includeUnstaged, notifications
- Add button disable during generation with progress indicator
- Add sparkle icon for the action button
- Include package.json, tsconfig, and basic project setup

.editorconfig

@@ -0,0 +1,12 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = false
+insert_final_newline = false