T01 primitives: image, divider, backdrop, focus, pressable, measure, tooltip

Ely-built primitives plus gallery demos for every chapter-one entry,
including gpui natives. The gallery now scripts real input by posting
NSEvents to its own queue and shoots each interaction in both modes.
Codex gpt-6-astra (max): three rounds; the last finding, a two-line
doc comment, was fixed after the three-review cap.

tasks/ch31-43.md

@@ -289,4 +289,4 @@
 - [ ] DesignTokenViewer
 - [ ] IconBrowser
 - [ ] A11yChecker — contrast audit
-- [ ] ScreenshotTest Harness — self-capture
+- [ ] ScreenshotTest Harness — self-capture; scripted input since T01