feat(gpui): load markdown network images and land 1.1.0 shell parity

Register a ureq HttpClient so document tabs can fetch http(s) images. Also lands OSC 8/URL links, configurable terminal bell, and the rest of the 1.1.0 GPUI changelog.

nebula_split/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nebula-split"
-version = "1.0.0"
+version = "1.1.0"
 license = "GPL-3.0-or-later"
 description = "Shared split-pane rules: layout tree, geometry, divider drag and directional focus"
 publish = false