build: add Meson wrapper for libghostty-vt

Add Meson build system integration mirroring the existing CMake
wrapper. The top-level meson.build delegates to zig build lib-vt
using --prefix-lib-dir and --prefix-include-dir to place outputs
directly in the Meson build directory, avoiding stamp files and
source tree pollution. A sentinel .h output ensures Meson orders
the zig build before any downstream compiles.

Downstream projects can consume the library either as a Meson
subproject via a .wrap file or through pkg-config after install.
The dist/meson/README.md documents both approaches.

Includes a c-vt-meson example, CI job in test.yml for auto-discovered
Meson examples, meson and ninja in the nix devShell, and gitignore
updates for Meson build artifacts.

example/.gitignore

@@ -2,4 +2,8 @@
 dist/
 node_modules/
 example.wasm*
+# CMake / Meson
 build/
+
+# Meson
+subprojects/

example/c-vt-meson/README.md

@@ -0,0 +1,42 @@
+# c-vt-meson
+
+Demonstrates consuming libghostty-vt from a Meson project using a
+subproject. Creates a terminal, writes VT sequences into it, and
+formats the screen contents as plain text.
+
+## Building this example
+
+Since this example lives inside the Ghostty repo, point the subproject
+at the local checkout instead of fetching from GitHub:
+
+```shell-session
+cd example/c-vt-meson
+mkdir -p subprojects
+ln -s ../../.. subprojects/ghostty
+meson setup build
+meson compile -C build
+./build/c_vt_meson
+```
+
+## Real World Usage
+
+Create a `subprojects/ghostty.wrap` file in your project:
+
+```ini
+[wrap-git]
+url = https://github.com/ghostty-org/ghostty.git
+revision = main
+depth = 1
+```
+
+Then in your `meson.build`:
+
+```meson
+ghostty_proj = subproject('ghostty')
+ghostty_vt_dep = ghostty_proj.get_variable('ghostty_vt_dep')
+
+executable('myapp', 'src/main.c', dependencies: ghostty_vt_dep)
+```
+
+Meson will clone the repository into `subprojects/ghostty/` on first
+build and invoke `zig build lib-vt` automatically.

example/c-vt-meson/meson.build

@@ -0,0 +1,11 @@
+project('c-vt-meson', 'c',
+    version: '0.1.0',
+    meson_version: '>= 1.1.0',
+)
+
+ghostty_proj = subproject('ghostty')
+ghostty_vt_dep = ghostty_proj.get_variable('ghostty_vt_dep')
+
+executable('c_vt_meson', 'src/main.c',
+    dependencies: ghostty_vt_dep,
+)

example/c-vt-meson/src/main.c

@@ -0,0 +1,52 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ghostty/vt.h>
+
+int main() {
+  // Create a terminal with a small grid
+  GhosttyTerminal terminal;
+  GhosttyTerminalOptions opts = {
+    .cols = 80,
+    .rows = 24,
+    .max_scrollback = 0,
+  };
+  GhosttyResult result = ghostty_terminal_new(NULL, &terminal, opts);
+  assert(result == GHOSTTY_SUCCESS);
+
+  // Write some VT-encoded content into the terminal
+  const char *commands[] = {
+    "Hello from a \033[1mMeson\033[0m-built program!\r\n",
+    "Line 2: \033[4munderlined\033[0m text\r\n",
+    "Line 3: \033[31mred\033[0m \033[32mgreen\033[0m \033[34mblue\033[0m\r\n",
+  };
+  for (size_t i = 0; i < sizeof(commands) / sizeof(commands[0]); i++) {
+    ghostty_terminal_vt_write(terminal, (const uint8_t *)commands[i],
+                              strlen(commands[i]));
+  }
+
+  // Format the terminal contents as plain text
+  GhosttyFormatterTerminalOptions fmt_opts =
+      GHOSTTY_INIT_SIZED(GhosttyFormatterTerminalOptions);
+  fmt_opts.emit = GHOSTTY_FORMATTER_FORMAT_PLAIN;
+  fmt_opts.trim = true;
+
+  GhosttyFormatter formatter;
+  result = ghostty_formatter_terminal_new(NULL, &formatter, terminal, fmt_opts);
+  assert(result == GHOSTTY_SUCCESS);
+
+  uint8_t *buf = NULL;
+  size_t len = 0;
+  result = ghostty_formatter_format_alloc(formatter, NULL, &buf, &len);
+  assert(result == GHOSTTY_SUCCESS);
+
+  printf("Plain text (%zu bytes):\n", len);
+  fwrite(buf, 1, len, stdout);
+  printf("\n");
+
+  free(buf);
+  ghostty_formatter_free(formatter);
+  ghostty_terminal_free(terminal);
+  return 0;
+}