Add branch creation and file history search

Implement the ability to create new local branches directly from the application's UI. This includes a new backend command to handle branch creation with validation and a frontend form in the branch panel.

Additionally, extend the global search dialog to include a "Files" tab. Users can now search for files by name or path within the repository. Selecting a file in the search results displays its full commit history, with options to diff the file at a specific commit or restore it to that version.

src/App.svelte

@@ -23,6 +23,7 @@
     commit,
     compareCommits,
     cancelCodeSearch,
+    createBranch,
     diffFileAgainstWorkingTree,
     compareFileToParent,
     getStatus,
@@ -413,6 +414,18 @@
     });
   }
 
+  async function createNewBranch(branchName: string) {
+    const name = branchName.trim();
+    if (!activeRepoPath || !name) return;
+    await runOperation(`Creating ${name}`, async () => {
+      applyStatus(await createBranch(activeRepoPath, name));
+      await refreshBranchList(activeRepoPath);
+      await refreshCommitHistory(activeRepoPath);
+      await refreshExplorerFiles(activeRepoPath);
+      await refreshFileHistory(activeRepoPath);
+    });
+  }
+
   async function merge(branch: GitBranchInfo) {
     if (!activeRepoPath || branch.current) return;
     await runOperation(`Merging ${branch.name}`, async () => {
@@ -719,6 +732,17 @@
     expandedExplorerPaths = new Set();
   }
 
+  function explorerParentFolders(path: string): string[] {
+    const parts = normalizeExplorerPath(path).split("/").filter(Boolean);
+    const folders: string[] = [];
+    let current = "";
+    for (let index = 0; index < parts.length - 1; index++) {
+      current = current ? `${current}/${parts[index]}` : parts[index];
+      folders.push(current);
+    }
+    return folders;
+  }
+
   async function selectExplorerNode(node: ExplorerNode) {
     if (!activeRepoPath || (selectedExplorerPath === node.path && selectedExplorerKind === node.kind)) return;
     selectedExplorerPath = node.path;
@@ -728,6 +752,17 @@
     });
   }
 
+  async function selectFileFromSearch(file: GitRepositoryFile) {
+    if (!activeRepoPath) return;
+    selectedExplorerPath = file.path;
+    selectedExplorerKind = "file";
+    expandedExplorerPaths = new Set([...expandedExplorerPaths, ...explorerParentFolders(file.path)]);
+
+    await runOperation(`Loading ${file.path} history`, async () => {
+      await refreshFileHistory(activeRepoPath, file.path);
+    });
+  }
+
   async function restoreSelectedFileFromCommit(target: GitCommit) {
     if (!activeRepoPath || !selectedExplorerPath) return;
     const kind = selectedExplorerKind === "folder" ? "folder" : "file";
@@ -1009,6 +1044,7 @@
           {isBusy}
           onCheckout={checkout}
           onMerge={merge}
+          onCreateBranch={createNewBranch}
         />
         <ExplorerPanel
           {repoFiles}
@@ -1133,10 +1169,16 @@
     isSearching={globalSearchBusy}
     error={globalSearchError}
     results={globalSearchResults}
+    files={repoFiles}
+    fileHistory={fileHistory}
+    selectedFilePath={selectedExplorerPath}
     onClose={closeGlobalSearchDialog}
     onSearch={runGlobalSearch}
     onCancel={cancelGlobalSearch}
     onDiff={diffSearchHit}
+    onSelectFile={selectFileFromSearch}
+    onFileHistoryDiff={diffSelectedFileFromCommit}
+    onFileHistoryRestore={restoreSelectedFileFromCommit}
   />
 {/if}