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.

Cargo.lock

@@ -1519,6 +1519,7 @@ name = "ely-gpui-component"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "cocoa 0.26.0",
  "core-foundation 0.10.0",
  "core-graphics 0.24.0",
  "env_logger",
@@ -1526,6 +1527,7 @@ dependencies = [
  "image",
  "log",
  "rust-embed",
+ "smallvec",
 ]
 
 [[package]]