feat(story-mode): save as image, a helper's own steps, a way in on phones, and polish

- Save image: the page as one PNG to share (each panel canvas, then every
  caption, balloon and chip redrawn from its computed style and box).
- The helper drawer lists what the helper did, read live from its own
  transcript (GET .../story/helpers/:agentId), led by the task Claude gave it.
- Session Options has a Story button (same setting), the way in on phones.
- A turn a background task or another session started reads as a notice,
  not as your speech balloon.
- Wide panels keep their scene in a centered stage instead of spreading the
  art to both ends; the fix panel's agent stands next to the page.
- An unchanged page (same ETag) is neither parsed nor redrawn.
- Paths inside the session's folder are shown short; clicks keep full paths.
- Tab stays inside the overlay; a missing 2D context skips the art, not the page.
- A rebindable Story Mode shortcut (no default chord).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/wiki/Settings-Reference.md

@@ -69,8 +69,9 @@ Ultracode Windows, Cron.
 draws the active Claude Code session as a comic: one page per prompt, panels for what Claude
 did (reading, planning, helpers, edits, tests, saving), and plain captions anyone can follow.
 The **Director's cut** switch names every tool call instead. Click a file to open it, the code
-page for the exact diff, a test board for the output. An unfinished turn redraws as Claude
-works.
+page for the exact diff, a test board for the output, a helper for what it was asked and what
+it did. An unfinished turn redraws as Claude works, and **Save image** downloads the page as a
+PNG to share. On phones, open it from the session's Session Options (the Story button there).
 
 **Bottom bar** (below the chips): **Git status** shows a small indicator at the right of the
 bottom bar, off by default and per device. It reads `● N` uncommitted files, `↑ N` commits not