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)

crates/ghostty-cli/src/ssh_cache.rs

@@ -216,6 +216,10 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(
+        wine,
+        ignore = "wine: ntdll NtSetInformationFile(FileRenameInformationEx, REPLACE_IF_EXISTS|POSIX_SEMANTICS) is unsupported (\"unsupported flags: 0x3\"), so std::fs::rename over an existing file fails with ERROR_ACCESS_DENIED; real Windows supports it"
+    )]
     fn add_list_host_remove_clear() {
         let tmp = tempfile::tempdir().unwrap();
         let cache = DiskCache {