feat(vcs): Add a modal commit mode and fill in Git log, branch popup and settings (#144)

- Settings › Commit › "Use non-modal commit interface": when off, Local
  Changes, Shelf and Stash become tabs of the Git tool window and ⌘K opens
  a Commit dialog; switches live.
- Git tool window: Worktrees tab; Show History and Show Git Log for a
  branch open their own closable tabs instead of changing the Log filters.
- Log: toolbar and context menu for a commit's changed files, vertical
  toolbar, Tags node and hiding for the branches pane, Collapse / Expand
  Linear Branches as separate actions, and a Version Control › Log page.
- Branch popup: collapsible groups, branches grouped by prefix, an options
  menu behind the gear, incoming / outgoing icons and "Pull into … Using
  Rebase / Merge"; New Branch on ⌥⌘N outside the editor.
- Git main menu regrouped with Uncommitted Changes and Current File
  submenus; rebase / merge controls enabled only while one is in progress.
- Settings: Version Control lists its pages; new options for clearing the
  initial commit message, showing Update options, confirming dropped
  commits, revealing created patches, large-file and file-name warnings,
  the Push dialog after Commit and Push, combined stashes and shelves, and
  removing applied files from the shelf.

src/features/vcs/GitLog.module.css

@@ -28,9 +28,23 @@
 .branches {
   height: 100%;
   display: flex;
-  flex-direction: column;
   min-width: 0;
 }
+.branchesTools {
+  flex: none;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 2px;
+  padding: 4px 2px;
+  border-right: 1px solid var(--border);
+}
+.branchesMain {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+}
 .branchesBar,
 .filters,
 .detailsBar {
@@ -472,3 +486,17 @@
 .branchFilterMore:hover {
   background: var(--bg-tree-hover);
 }
+/* Worktrees tab. */
+.worktrees {
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  padding: 4px 6px;
+}
+.worktreeList {
+  flex: 1;
+  min-height: 0;
+  overflow: auto;
+}