ludic ui-preview: ludic.ui components previewed for a studio over stdio (R5)

A prebuilt tool, bin/ludic-ui-preview (built by ludic-dev build, shipped beside ludic-lsp, run as
`ludic ui-preview [--font DIR]`): ludic.ui with a backend that records every draw call as a line,
and mock component classes the studio describes (load / model / calls). frame t runs ui_show at
interface time t; text is measured on the CPU with the game's font.json metrics; locale goes
through ludic.i18n; tree / box / rules inspect the frame. No game code, no GPU, no network. The wire
protocol is frozen as tools/ui-preview/protocol-v1.md; smoke.txt is a transcript to run.

ludic.ui gains, all additive: UiClass.make_of, UiBackend.said / emitted, UiRule.text / at (with
comment line breaks kept so rule lines count true, and a class's styles read under its .lss path),
and ui_root, ui_find, ui_rules_of, ui_rule_value, ui_building, ui_class, ui_class_load,
ui_file_forget, ui_errors_clear; ui_nine_cuts_into exported.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/ludic-cli/release.ludic

@@ -324,7 +324,7 @@ function build_artifacts(ver: pointer) -> bool {
     let name = `ludic-{ver}-{plat}-{arch}`
     let stage = `{tmp_dir()}/{name}`
     shell(`rm -rf {stage} && mkdir -p {stage}/bin`)
-    if not shq(`cp bin/ludic bin/ludicc bin/ludic-fmt bin/ludic-lsp {stage}/bin/`) {
+    if not shq(`cp bin/ludic bin/ludicc bin/ludic-fmt bin/ludic-lsp bin/ludic-ui-preview {stage}/bin/`) {
       err("release: the toolchain is not built (run: ludic-dev build)\n")
       return false
     }