fix: inspector font/formatting, FreeType-only backend on Apple

Resolves the parity items of docs/rewrite/notes/review-rv17-codex.md
(final-Z20.md):
- FreeType-only font backend is also available on Apple targets
  (discovery-free, embedded emoji fonts); ghostty_surface_quicklook_font
  returns null for every backend except plain CoreText like Zig.
- The +list-fonts test keys off the font crate's selected backend
  (HAS_DISCOVERY), correct under feature unification and on Apple.
- Inspector font: 32 px rasterized with FreeType (dear-imgui freetype)
  like Ghostty; a new `visual-parity.sh inspector` scenario shows 0.031%
  differing pixels (hover highlight) vs the original on Linux. Windows,
  Apple and wasm keep stb_truetype at 32 px (registered as a deliberate
  deviation).
- Inspector DCS/APC descriptions follow Zig 0.15.2's formatting
  (checked by running Zig), incl. the terminal.Parser.Action prefix.
- The ImGui demo window appears only in dev-profile builds, mirroring
  Zig's .Debug-only gate.

Test Plan:
- cargo test --workspace --no-fail-fast (3582 passed)
- just check-macos (both, also with --features font-backend-freetype)
- scripts/visual-parity.sh inspector

crates/ghostty-inspector/Cargo.toml

@@ -13,6 +13,13 @@ ghostty-terminal.workspace = true
 ghostty-vt.workspace = true
 log = "0.4"
 
+# Zig builds Dear ImGui with `-DIMGUI_ENABLE_FREETYPE` (pkg/dcimgui), so the
+# inspector font is rasterized with FreeType. The `freetype` feature needs a
+# system FreeType (pkg-config); other targets keep stb_truetype (see
+# `docs/rewrite/DEVIANT_FIXES.md`).
+[target.'cfg(not(any(windows, target_vendor = "apple", target_arch = "wasm32")))'.dependencies]
+dear-imgui-rs = { version = "0.19", features = ["freetype"] }
+
 [lints.rust]
 unsafe_code = "deny"