feat(lanes,run,pricing): Changes sidebar editor, staged groups, image drop, auto pricing

- Changes panel at full screen: the whole Files view (finder, expand-all,
  tree) becomes a left sidebar and the Files tab is dropped; a working-copy
  file opens straight into the editor (Save/Cancel live once the text
  differs, Cancel restores it, Whole file toggles back to the diff), and the
  page is height-locked so the editor no longer collapses with no live run.
- Overview splits into Staged Changes / Changes groups in the work range.
- A changed file's whole tree row takes its status tint.
- Drag an image onto the lane terminal: POST /api/run/drop-image saves it
  (png/jpeg/gif/webp, random name, 0600, pruned after a day) and the path
  is pasted into the pane, which is how claude attaches it.
- Claude Opus 5.5 gets its own pricing row (4/20/0.2/5/8, fast 8/40);
  claude-opus-5% had been pricing it as Opus 5.
- server/lib/pricing-sync.js: a model family used in token_usage with no
  row of its own is inserted from LiteLLM's public price list, never
  updated; off with AGENTHUB_PRICING_SYNC=0. repo-links allows exactly
  that one third-party GitHub raw URL.

client/src/pages/Workspace.tsx

@@ -583,8 +583,11 @@ export function Workspace() {
 
   // Viewport locked only when a live run is showing (TerminalView needs locked
   // viewport for chat scrolling). The config-card screen needs normal page flow
-  // so the form is fully reachable on short windows.
-  const viewportLocked = paneHasActiveRun;
+  // so the form is fully reachable on short windows. A full-width Changes panel
+  // hides that form anyway, and without a locked height it shrinks to its
+  // content — the editor inside it collapsed to a few lines (no live run).
+  const viewportLocked =
+    paneHasActiveRun || (!!currentLane && changesOpen && changesSize === "full");
 
   const handleLaneAction = async (id: number, action: string, body?: Record<string, unknown>) => {
     setLaneActionError(null);
@@ -1032,6 +1035,7 @@ export function Workspace() {
                 </div>
                 <LaneChangesPanel
                   laneId={currentLane.id}
+                  full={changesSize === "full"}
                   // A sibling worktree forks from the lane's SOURCE repo when
                   // it has one (this lane is itself a worktree of it); an
                   // adopted lane is its own repo.