Remove the SyntaxMate XPC service

[dayglojesus]

Removes the SyntaxMate XPC service, at the request of its author.

Why

SyntaxMate is an XPC service that hands a syntax-highlighted NSAttributedString back to a calling application. Vadim Shpakovski contributed it in 2016 and asked for its removal in 2023 (textmate#1462):

Hi Team, this tool is not embedded into the main app and did not find a use as we expected. We should probably remove it.

That PR is still open upstream. This applies his commit to our fork, authorship preserved.

I checked the state of it here before agreeing:

• Nothing references it. No other rave target requires it, no in-tree caller mentions it, and it is not embedded in TextMate.app.
• CI never compiles it. build-and-test.yml and release.yml both run ninja TextMate, which does not reach the SyntaxMate target. It could have been broken for years without anyone noticing.
• Its submodule is a dead dependency. Applications/SyntaxMate/resources/SyntaxMate.tmBundle points at shpakovski/syntaxmate.tmbundle, archived since 2016-11-13. It still resolves today, but it is an unowned single point of failure in every recursive clone — the same failure mode that currently makes textmate#1469 unbuildable for anyone but its author.
• 4.6 MB and 235 .tmLanguage files in every clone, for a target nobody builds.
• SyntaxMateImpl.mm uses initForReadingWithData:, deprecated since macOS 10.14.

In fairness to the other side: it does still build. ninja SyntaxMate completes and signs SyntaxMate.xpc cleanly on macOS 26.5 / Xcode 26.4. This is not bitrot — it is a working component with no consumer, kept alive by luck rather than by CI. If we ever want a third-party integration surface again, the code is recoverable from history, and it would need to come back with CI coverage and vendored grammars rather than an archived submodule.

What

 .gitmodules                                        |   3 -
 Applications/SyntaxMate/Info.plist                 |  25 -
 Applications/SyntaxMate/default.rave               |  11 -
 Applications/SyntaxMate/resources/Default.tmProperties |   8 -
 Applications/SyntaxMate/resources/SyntaxMate.tmBundle  |   1 -
 Applications/SyntaxMate/src/SyntaxMate.h           |  41 -
 Applications/SyntaxMate/src/SyntaxMateImpl.h       |   7 -
 Applications/SyntaxMate/src/SyntaxMateImpl.mm      | 129 -
 Applications/SyntaxMate/src/main.mm                |  57 -

This drops our submodule count from 7 to 6.

Verification

macOS 26.5, Xcode 26.4.

• grep -rn SyntaxMate across *.rave, *.yml, *.md and all sources: no dangling references.
• After ./configure, SyntaxMate is no longer a ninja target (was 6: SyntaxMate, /debug, /release, /run, …).
• ninja TextMate — exit 0, clean.
• Fresh clone of this branch + git submodule update --init --recursive — exit 0, six submodules, no Applications/SyntaxMate. This is the check that matters for a submodule removal, and it is the one that would have caught the broken pins in My take on modernizing TextMate textmate/textmate#1469.