feat(blame): add file blame dialog with git porcelain parsing

This change introduces a new backend command to fetch file blame using
git's line-porcelain output and returns structured per-line metadata.
The UI adds a BlameDialog that groups lines by commit, highlights
uncommitted changes, and styles the dialog to match the updated theme.

- Add get_file_blame command and parsing with uncommitted detection
- Wire BlameDialog into the explorer file node actions
- Add blame UI component and supporting types and styles

src-tauri/src/main.rs

@@ -10,8 +10,8 @@ use git::{
     cherry_pick_continue, clone_repository, commit, commit_ai_generate, commit_ai_load,
     commit_ai_local_models, commit_ai_status, compare_commits, compare_file_to_head,
     compare_file_to_parent, create_branch, create_tag, cred_delete, cred_load, cred_save,
-    delete_branch, delete_tag, diff_file_against_working_tree, fetch, get_file_patch,
-    get_remote_url, get_status, last_commit_message, list_branches, list_commits,
+    delete_branch, delete_tag, diff_file_against_working_tree, fetch, get_file_blame,
+    get_file_patch, get_remote_url, get_status, last_commit_message, list_branches, list_commits,
     list_file_history, list_repository_files, list_stashes, list_tags, merge_branch,
     open_repo_in_explorer, open_repository, open_repository_bundle, open_repository_file, pull,
     push, push_tag, read_conflict, rebase_abort, rebase_branch, rebase_continue, rename_branch,
@@ -76,6 +76,7 @@ fn main() {
             open_repository_bundle,
             list_file_history,
             cancel_file_history,
+            get_file_blame,
             compare_commits,
             compare_file_to_head,
             compare_file_to_parent,