Add code-token VisualRoles and Code view

[Copilot]

Fixes

Adds theme-driven token roles for syntax-highlighted code so Markdown, the new Code view, and downstream editors can share the active Terminal.Gui theme palette.

Proposed Changes/Todos

• Code token roles

  • Added VisualRole.CodeComment through CodeAttribute.
  • Added Scheme storage, JSON round-trip support, and fallback: Code* → Code → Editable → Normal.

• Theme/config support

  • Added Dark/Light Base.Code* colors.
  • Updated config schema.
  • Added Examples/Themes/code-dark.config.json.

• Rendering pipeline

  • TextMateSyntaxHighlighter now emits StyledSegment.Role.
  • Markdown code blocks resolve token attributes from VisualRole.Code*.
  • Added public Code view:

Code code = new ()
{
    Language = "cs",
    Text = "public string Name => \"Ada\";"
};

• UICatalog

  • Expanded Themes scenario with Code role swatches and live Markdown code.
  • Added Code View Demo scenario.

• Tests

  • Added/updated coverage for Scheme derivation, JSON conversion, TextMate scope mapping, Markdown pipeline, and Code rendering.
  • Perf benchmark comparison remains pending on baseline benchmark availability in this checkout.

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui - if you use Visual Studio, hit CTRL-K-D to automatically reformat your files before committing.
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• accounts.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=network --no-sandbox --use-angle=swiftshader-webgl --crashpad-handler-pid=7412 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/org.chromium.Chromium.scoped_dir.0Zz0qB --change-stack-guard-on-fork=enable --shared-files=network_parent_dirs_pipe:100,v8_context_snapshot_data:101 --field-trial-handle=3,i,18362738395879841708,9124006556522462828,262144 --disable-features=PaintHolding --variations-seed-version --pseudonymization-salt-handle=7,i,3170967420076418732,10802322850313536385,4 --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /usr/bin/chromium chromium --headless --no-sandbox --disable-gpu --screenshot=/tmp/tg-ui/code-demo.png --window-size=1000,500 file:///tmp/tg-ui/code-demo.html (dns block)
• clients2.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=network --no-sandbox --use-angle=swiftshader-webgl --crashpad-handler-pid=7412 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/org.chromium.Chromium.scoped_dir.0Zz0qB --change-stack-guard-on-fork=enable --shared-files=network_parent_dirs_pipe:100,v8_context_snapshot_data:101 --field-trial-handle=3,i,18362738395879841708,9124006556522462828,262144 --disable-features=PaintHolding --variations-seed-version --pseudonymization-salt-handle=7,i,3170967420076418732,10802322850313536385,4 --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /usr/bin/chromium chromium --headless --no-sandbox --disable-gpu --screenshot=/tmp/tg-ui/code-demo.png --window-size=1000,500 file:///tmp/tg-ui/code-demo.html (dns block)
• redirector.gvt1.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=network --no-sandbox --use-angle=swiftshader-webgl --crashpad-handler-pid=7412 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/org.chromium.Chromium.scoped_dir.0Zz0qB --change-stack-guard-on-fork=enable --shared-files=network_parent_dirs_pipe:100,v8_context_snapshot_data:101 --field-trial-handle=3,i,18362738395879841708,9124006556522462828,262144 --disable-features=PaintHolding --variations-seed-version --pseudonymization-salt-handle=7,i,3170967420076418732,10802322850313536385,4 --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /usr/bin/chromium chromium --headless --no-sandbox --disable-gpu --screenshot=/tmp/tg-ui/code-demo.png --window-size=1000,500 file:///tmp/tg-ui/code-demo.html (dns block)
• www.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=network --no-sandbox --use-angle=swiftshader-webgl --crashpad-handler-pid=7412 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/org.chromium.Chromium.scoped_dir.0Zz0qB --change-stack-guard-on-fork=enable --shared-files=network_parent_dirs_pipe:100,v8_context_snapshot_data:101 --field-trial-handle=3,i,18362738395879841708,9124006556522462828,262144 --disable-features=PaintHolding --variations-seed-version --pseudonymization-salt-handle=7,i,3170967420076418732,10802322850313536385,4 --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /usr/bin/chromium chromium --headless --no-sandbox --disable-gpu --screenshot=/tmp/tg-ui/code-demo.png --window-size=1000,500 file:///tmp/tg-ui/code-demo.html (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)