[aetoskevin]

Fixes #1071.

A mod can now write TextView.markdown(id, text).raw_html(false) to show any HTML in the Markdown as the text it is written as. Autolinks stay links, and the default is unchanged.

• vendor/gpui-kit/crates/base: backports gpui-kit text: Add an option to keep raw HTML in Markdown as text longbridge/gpui-kit#3979 (MarkdownExtensions::raw_html, TextView::markdown_raw_html and its test), marked HERDR:. It's reviewed there and not yet merged; once herdr-app's vendored gpui-kit includes it, this backport goes away.
• vendor/gpui-kit/crates/shell:
  • a raw_html behavior, registered where selectable and scrollable are;
  • applied as markdown_raw_html when the TextView is built;
  • declared on TextViewElement in the generated .d.ts.
• defaults/AGENTS.md: one line on .raw_html(false).

Tests:

• the typings test checks that raw_html( is declared on TextViewElement only;
• the render test checks that the behavior is recorded (:raw_html);
• the vendored gpui-base test covers the parser.

How it was tested (macOS 26.6.2 ARM64), running the vendored crates' tests resolved through Herdr's Cargo.lock and patches:

• gpui-base's new test passes, along with all 1329 of its unit tests. The vendored unit tests need gpui-kit's README.md, which a test reads with include_str! and which isn't vendored, so I put it in place for the run.
• In gpui-shell, the text_view and typings tests pass.
• gpui-shell's lib suite gives the same results with and without this change: 702 pass, and the same 5 fail on master (5216e6f) without it, among them typings::tests::every_element_method_is_accounted_for (3208 declared style methods against 3207 in the runtime's table).
• herdr-app's own cargo test --locked passes (Rust 1.100.0, Zig 0.16.0). It doesn't run the vendored crates' tests, because the workspace excludes vendor/gpui-kit; hence the runs above.

Written with AI (Claude).