feat(git): add rebase workflow with UI state handling

This introduces Git rebase commands (start, continue, abort) and
exposes whether a rebase is currently in progress via the status
payload. The UI now blocks committing during an active rebase and
shows a dedicated rebase notice with continue/abort actions.

- Add tauri commands for rebase operations and status detection
- Update frontend to render rebase state and controls
- Adjust conflict/resolution messaging and related UI styling

src/lib/components/BranchPanel.svelte

@@ -49,6 +49,7 @@
     isBusy: boolean;
     onCheckout: (branch: GitBranchInfo) => void;
     onMerge: (branch: GitBranchInfo) => void;
+    onRebase: (branch: GitBranchInfo) => void;
     onCreateBranch: (branchName: string) => void | Promise<void>;
     onRenameBranch: (branch: GitBranchInfo) => void | Promise<void>;
     onDeleteBranch: (branch: GitBranchInfo) => void | Promise<void>;
@@ -62,6 +63,7 @@
     isBusy = false,
     onCheckout = () => {},
     onMerge = () => {},
+    onRebase = () => {},
     onCreateBranch = () => {},
     onRenameBranch = () => {},
     onDeleteBranch = () => {},
@@ -370,6 +372,10 @@
                         <GitMerge size={15} aria-hidden="true" />
                         Merge
                       </button>
+                      <button class="btn-sm" type="button" onclick={() => onRebase(row.branch)} disabled={isBusy} title="Rebase current branch onto this branch">
+                        <GitBranch size={15} aria-hidden="true" />
+                        Rebase
+                      </button>
                     </div>
                   {/if}
                 </article>
@@ -446,6 +452,10 @@
                         <GitMerge size={15} aria-hidden="true" />
                         Merge
                       </button>
+                      <button class="btn-sm" type="button" onclick={() => onRebase(row.branch)} disabled={isBusy} title="Rebase current branch onto this branch">
+                        <GitBranch size={15} aria-hidden="true" />
+                        Rebase
+                      </button>
                     </div>
                   {/if}
                 </article>

src/lib/components/ResolveDialog.svelte

@@ -261,13 +261,13 @@
     style="grid-template-rows: auto minmax(0,1fr) auto;"
     role="dialog"
     aria-modal="true"
-    aria-label="Resolve merge conflicts"
+    aria-label="Resolve conflicts"
     tabindex="-1"
   >
     <header class="dialog-header">
       <div>
         <span class="eyebrow">Resolve</span>
-        <h2 class="dialog-title">Merge conflicts</h2>
+        <h2 class="dialog-title">Conflicts</h2>
       </div>
       <button class="dialog-close" type="button" onclick={onClose} title="Close">
         <X size={18} aria-hidden="true" />
@@ -275,7 +275,7 @@
     </header>
 
     {#if conflictedFiles.length === 0}
-      <div class="blank-state">All conflicts resolved. You can commit the merge now.</div>
+      <div class="blank-state">All conflicts resolved. Continue the current operation when ready.</div>
     {:else}
       <div class="dialog-body">
         <aside class="dialog-files" aria-label="Conflicted files">

src/lib/components/StashPanel.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { Archive, Download, Trash2, Upload } from "@lucide/svelte";
+  import { Archive, ChevronDown, ChevronRight, Download, Trash2, Upload } from "@lucide/svelte";
   import type { GitStash } from "../types";
 
   interface Props {
@@ -26,6 +26,7 @@
 
   let message = $state("");
   let includeUntracked = $state(true);
+  let open = $state(false);
 
   function submitPush() {
     onPush(message, includeUntracked);
@@ -37,16 +38,33 @@
   }
 </script>
 
-<section class="panel stash-panel overflow-hidden" aria-label="Git stash">
+<section class="panel stash-panel overflow-hidden" class:collapsed={!open} aria-label="Git stash">
   <div class="section-head">
     <div>
       <span class="eyebrow">Stash</span>
       <h2 class="mt-0.5 text-ink text-base font-bold leading-tight">Shelved changes</h2>
     </div>
-    <span class="pill pill-count">{stashes.length}</span>
+    <div class="stash-head-actions">
+      <button
+        class="stash-toggle"
+        type="button"
+        onclick={() => { open = !open; }}
+        aria-expanded={open}
+        title={open ? "Collapse stash panel" : "Expand stash panel"}
+      >
+        {#if open}
+          <ChevronDown size={14} aria-hidden="true" />
+        {:else}
+          <ChevronRight size={14} aria-hidden="true" />
+        {/if}
+      </button>
+      <span class="pill pill-count">{stashes.length}</span>
+    </div>
   </div>
 
-  {#if !hasRepository}
+  {#if !open}
+    <!-- collapsed -->
+  {:else if !hasRepository}
     <div class="blank-state">No repository loaded.</div>
   {:else}
     <div class="stash-create">