chore(injections): rebase onto main (#120 themes stage 1 / v16)

Rebase the injection branch onto main after #120 (themes stage 1,
protocol v16) merged. Conflicts were confined to appended test blocks
in pmacs-gpu/src/main.rs (kept both #120's GPU face tests and the
injection source_color test); highlight.rs, lua_bindings/mod.rs, and
semantic_render.rs auto-merged (my injection code and #120's theme
epochs / resolve_faces summary path / ThemeFacts occupy disjoint
regions). The one API adaptation: #120 gave scoped_file_summary a
`resolve_faces: bool` parameter, so the full-buffer flatten perf gate
passes `false` (it exercises the syntax flatten path).

Gates re-run on the rebased base: fmt, clippy -D warnings, lib (1582),
lib crdt (1756), m4 (110), theme_faces (22, #120's suite unbroken),
PMACS_REQUIRE_GPU gpu (70), full workspace sweep (0 failures),
git diff --check.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YJ9FQ832QwftJXCD9LeFan

src/semantic_render.rs

@@ -3515,7 +3515,7 @@ mod tests {
         seed_rust_parse_view(&state, bid, src.as_bytes());
 
         let start = std::time::Instant::now();
-        let summary = scoped_file_summary(&state, bid);
+        let summary = scoped_file_summary(&state, bid, false);
         let elapsed = start.elapsed();
         assert!(!summary.is_empty(), "summary produced for a styled buffer");
         assert!(