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.

docs/API.md

@@ -1994,6 +1994,7 @@ GET    /api/run/binary?tool=          { found, path } for the `claude` or `codex
 GET    /api/run/cwds                  Suggested cwds (dashboard, home, recent)
 GET    /api/run/history?limit=&laneId=  Persisted run history; laneId narrows to one lane's runs
 GET    /api/run/files?cwd=&q=         Fuzzy file search inside cwd for the @-file autocomplete
+POST   /api/run/drop-image            Raw image body (png/jpeg/gif/webp, ≤20 MB) → {path}: saved 0600 under <tmpdir>/agenthub-drops-<uid>/ with a random name, pruned after a day; the terminal pastes the path
                                        (skips node_modules, .git, dist, build, .next, .cache, coverage, vendor)
 POST   /api/run                       Start/attach run — Body: { laneId, cwd?, model?, permissionMode?, effort?, resumeSessionId?, initialPrompt? }
 GET    /api/run/:id                   Run handle (returns live run state)