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)

docs/rewrite/KNOWN_DIFFERENCES.md

@@ -1,24 +1,15 @@
 # Known differences (left by the stopping criterion)
 
-These are known minor differences between the Rust port and Ghostty 1.3.1
-found in the final audit (RV18, `notes/review-rv18-codex.md`). They were
-recorded, not fixed, because the stopping criterion in `PLAN.md` does not
-require chasing P3 items. All are severity P3. Each was verified from source
-and, where noted, by PTY reproduction.
-
-| # | Area | Rust | Zig | Observable effect | Sev |
-|---|------|------|-----|-------------------|-----|
-| 5 | Theme search: word navigation | `ghostty-cli/src/list_themes/preview.rs:113` has no word-navigation editing | upstream list-themes search has word navigation | Enter `blue red`, Alt+B, `X`: Zig gives `blue Xred`, Rust `blue redX` | P3 |
-| 6 | Theme search: grapheme backspace | `preview.rs:100` deletes one Unicode scalar | deletes one grapheme | `e` + U+0301 then Backspace: Zig removes both, Rust leaves `e` | P3 |
-| 7 | Theme search: non-ASCII case | `preview.rs:150` Unicode-lowercases theme names but ASCII-lowercases the query | ASCII-only on both sides | Query `Ä` does not match theme `Ä` in Rust, matches in Zig | P3 |
-| 8 | Theme preview: initial colors | `preview.rs:385` consults `COLORFGBG` | starts light until terminal color reports arrive | Without terminal replies, changing `COLORFGBG` changes Rust's colors only | P3 |
-| 9 | Theme preview: load errors | `preview.rs:440` ignores `load_file` errors and keeps filtering with the retained config | the error propagates and the preview exits | A config load error is silently swallowed in Rust | P3 |
-| 10 | Subprocess cleanup cap | `ghostty-termio/src/exec.rs:1348` waits at most about 5 s for the child's new process group | keeps waiting | If the child is delayed before `setsid` for longer, Rust returns without sending SIGHUP | P3 |
+All previously listed differences (rows 5-10: theme-search word navigation,
+grapheme backspace, ASCII-only case folding, initial preview colors, load_file
+error propagation, subprocess cleanup wait) have been fixed; see
+`notes/final-P3.md` (row 10 is registered as a deviant fix in
+`DEVIANT_FIXES.md`). No known differences are currently recorded here.
 
 ## Not verifiable on this machine
 
 - Native Apple execution: Metal, IOSurface, CoreText, Apple input APIs, Mach handling and Apple packaging (compile-checked only, `just check-macos`).
-- Windows ConPTY and Win32 behavior (compile-checked only, `just check-windows`).
+- Native Windows (real Windows console host, Windows-only APIs Wine stubs: `ResizePseudoConsole` is a Wine stub, POSIX-semantics rename over an existing file is unsupported by Wine). The Windows code paths are otherwise run under Wine (`just test-windows-wine`, see `notes/windows-wine.md`): ConPTY, `CreateProcessW`, pipes, the IO thread and `cmd.exe` children are runtime-tested; `just check-windows` stays the clippy gate.
 - Native FreeBSD execution (cross `cargo check` only, if the target could be added).
 - Live portal / D-Bus integration.
 - Real-browser rendering (wasm is checked with Node only).