You can pretty simply reproduce a crash on `main` in `Debug` mode by
running `printf "مرحبًا \n"` with your primary font set to one that
supports Arabic such as Cascadia Code/Mono or Kawkab Mono, which will
cause CoreText to output the shaped glyphs non-monotonically which hits
the assert we have in the renderer.

In `ReleaseFast` this assert is skipped and because we already moved
ahead to the space glyph (which belongs at the end but is emitted first)
all of the glyphs up to that point are lost. I believe this is probably
the cause of #8280, I tested and this change seems to fix it at least.

Included in this PR is a little optimization: we were allocating buffers
to copy glyphs etc. from runs to every time, even though CoreText
provides `CTRunGet*Ptr` functions which get *pointers* to the internal
storage of these values- these aren't guaranteed to return a usable
pointer but in that case we can always fall back to allocating again.
Also avoided allocation while processing glyphs by ensuring capacity
beforehand immediately after creating the `CTLine`.

The performance impact of this PR is negligible on my machine and
actually seems to be positive, probably due to avoiding allocations if I
had to guess.

The GLSL to MSL conversion process uses a passed-in sampler state for
the `iChannel0` parameter and we weren't providing it. This magically
worked on Apple Silicon for unknown reasons but failed on Intel GPUs.

In normal, hand-written MSL, we'd explicitly create the sampler state as
a normal variable (we do this in `shaders.metal` already!), but the
Shadertoy conversion stuff doesn't do this, probably because the exact
sampler parameters can't be safely known.

This fixes a Metal validation error when using custom shaders:

```
-[MTLDebugRenderCommandEncoder validateCommonDrawErrors:]:5970: failed 
assertion `Draw Errors Validation Fragment Function(main0): missing Sampler 
binding at index 0 for iChannel0Smplr[0].
```

Follow-up to #8720 adding

* Two improvements to FreeType glyph measurements:
- Ensuring that glyphs are measured with the same hinting as they are
rendered, ref
[#8720#issuecomment-3305408157](https://github.com/ghostty-org/ghostty/pull/8720#issuecomment-3305408157);
- For outline glyphs, using the outline bbox instead of the built-in
metrics, like `renderGlyph()`.
* Basic unit tests for face metrics and their estimators, using the
narrowest and widest fonts from the resource directory, Cozette Vector
and Geist Mono.

---

I also made one unrelated change to `freetype.zig`, replacing
`@alignCast(@ptrCast(...))` with `@ptrCast(@alignCast(...))` on line
173. Autoformatting has been making this change on every save for weeks,
and reverting the hunk before each commit is getting old, so I hope it's
OK that I use this PR to upstream this decree from the formatter.

Yet another low-hanging fruit

Hi there, this is just a low-hanging fruit and it also prepares the way
for the future 0.15, which removes addStaticLibrary.
Please, let me know what to do on the `// TODO` comments.

Found by Valgrind:

```
==265734== 320 bytes in 8 blocks are definitely lost in loss record 13,786 of 15,141
==265734==    at 0x5A65810: malloc (in /nix/store/l431jn8ahj09g5c1arrl7q6wcxngg21q-valgrind-3.24.0/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==265734==    by 0x3D799EB: onig_region_resize (.cache/zig/p/N-V-__8AAHjwMQDBXnLq3Q2QhaivE0kE2aD138vtX2Bq1g7c/src/regexec.c:923)
==265734==    by 0x3D81BCA: onig_region_resize_clear (.cache/zig/p/N-V-__8AAHjwMQDBXnLq3Q2QhaivE0kE2aD138vtX2Bq1g7c/src/regexec.c:949)
==265734==    by 0x3DA814F: search_in_range (.cache/zig/p/N-V-__8AAHjwMQDBXnLq3Q2QhaivE0kE2aD138vtX2Bq1g7c/src/regexec.c:5454)
==265734==    by 0x3DA7F25: onig_search (.cache/zig/p/N-V-__8AAHjwMQDBXnLq3Q2QhaivE0kE2aD138vtX2Bq1g7c/src/regexec.c:5414)
==265734==    by 0x382E7E8: regex.Regex.searchAdvanced (regex.zig:61)
==265734==    by 0x382E974: regex.Regex.search (regex.zig:48)
==265734==    by 0x382EC08: terminal.StringMap.SearchIterator.next (StringMap.zig:40)
==265734==    by 0x39ADDCD: renderer.link.Set.matchSetFromLinks (link.zig:320)
==265734==    by 0x39AE5C7: renderer.link.Set.matchSet (link.zig:95)
==265734==    by 0x39BCCE1: renderer.generic.Renderer(renderer.OpenGL).rebuildCells (generic.zig:2307)
==265734==    by 0x39C3BDB: renderer.generic.Renderer(renderer.OpenGL).updateFrame (generic.zig:1228)
==265734==    by 0x3993E88: renderer.Thread.renderCallback (Thread.zig:607)
==265734==    by 0x3993CFF: renderer.Thread.wakeupCallback (Thread.zig:524)
==265734==    by 0x39C522E: callback (async.zig:679)
==265734==    by 0x39C522E: watcher.async.AsyncEventFd(api.Xev(.io_uring,backend.io_uring)).waitPoll__anon_592685__struct_596870.callback (async.zig:181)
==265734==    by 0x3970EAE: backend.io_uring.Completion.invoke (io_uring.zig:804)
==265734==    by 0x3973AD8: backend.io_uring.Loop.tick___anon_586861 (io_uring.zig:193)
==265734==    by 0x3973BCD: backend.io_uring.Loop.run (io_uring.zig:84)
==265734==    by 0x3978673: dynamic.Xev(&.{ .io_uring, .epoll }[0..2]).Loop.run (dynamic.zig:172)
==265734==    by 0x3978972: renderer.Thread.threadMain_ (Thread.zig:263)
==265734==    by 0x3954580: renderer.Thread.threadMain (Thread.zig:202)
==265734==    by 0x39279CA: Thread.callFn__anon_573552 (Thread.zig:488)
==265734==    by 0x38F4594: Thread.PosixThreadImpl.spawn__anon_570448.Instance.entryFn (Thread.zig:757)
==265734==    by 0x6E567EA: start_thread (pthread_create.c:448)
==265734==    by 0x6ED9FB3: clone (clone.S:100)
==265734==
```

Related to #7879

This commit updates `zig build test` to run Xcode tests, too. These run
in parallel to the Zig tests, so they don't add any time to the test.

The Xcode tests will _not_ run when: (1) the target is not macOS, or (2)
the `-Dtest-filter` option is non-empty. This makes it so that this
change doesn't affect non-macOS and doesn't affect the general dev cycle
because you usually will run `-Dtest-filter` when developing a core
feature.

I didn't add a step to only run Xcode tests because I find that when I'm
working in Xcode I'm probably going to run the tests from there anyways.
The integration with `zig build test` is just a convenience, especially
around CI.

Speaking of CI, this change also makes it so this will run in CI.