test(windows): run the Windows code under Wine; theme preview parity

Windows was previously only compile-checked. With Wine 11 (staging)
and mingw available, scripts/windows-wine-test.sh (`just
test-windows-wine`) builds expat/FreeType/fontconfig for mingw under
target/wine-deps and runs the test suites of ghostty-vt, unicode,
datastruct, input, os, config, terminal, crash, termio and cli under
Wine (~2,700 tests). New termio/tests/exec_windows.rs drives real
cmd.exe children over ConPTY through Termio (output, exit codes,
typing, 120 KiB writes, stop, start failure). Fixes found: Windows
paths from fs::canonicalize leaked the \\?\ prefix (new
ghostty_os::path::realpath strips it like Zig); ghostty-font compiles
hb-ft for bundled HarfBuzz on Windows; ~25 tests had Unix assumptions.
Wine limitations are ignored with reasons (ResizePseudoConsole stub,
no POSIX rename over existing files) - docs/rewrite/notes/windows-wine.md.

+list-themes preview parity (former KNOWN_DIFFERENCES rows 5-9): the
search box ports vaxis TextInput (word navigation and editing bindings,
grapheme-wise editing), ASCII-only case folding, light initial colors
until terminal reports arrive (no COLORFGBG), and load errors end the
preview with exit 1; PTY tests compare with /usr/bin/ghostty.

Test Plan:
- just test-windows-wine
- cargo test -p ghostty-cli --test list_themes_pty
- cargo test --workspace --no-fail-fast (3601 passed)

Cargo.toml

@@ -29,7 +29,9 @@ ghostty-os.workspace = true
 log = "0.4"
 
 [dev-dependencies]
-rustix = { version = "1", features = ["process"] }
+ghostty-terminal.workspace = true
+ghostty-vt.workspace = true
+rustix = { version = "1", features = ["process", "pty", "termios", "fs", "stdio"] }
 serde_json = "1"
 tempfile = "3"
 
@@ -78,6 +80,8 @@ ghostty-lib = { path = "crates/ghostty-lib" }
 
 [workspace.lints.rust]
 unsafe_code = "forbid"
+# `--cfg wine` is set by scripts/windows-wine-test.sh to ignore Wine limitations.
+unexpected_cfgs = { level = "warn", check-cfg = ["cfg(wine)"] }
 
 [workspace.lints.clippy]
 pedantic = { level = "warn", priority = -1 }