fix: Windows core build, embedded init, byte-exact paths, version info

Closes the remaining core/lib/termio/GTK rows (final-Z2.md):
- ghostty-core compiles for Windows (Unix-only exec fields and file
  modes gated); checked with cargo check --target x86_64-pc-windows-gnu.
- Embedded init: ensure_locale, SIGPIPE ignored in ghostty_init for
  C/Swift hosts, Apple crash tags; the argv passed to ghostty_init feeds
  ghostty_config_load_cli_args; ghostty_config_load_file accepts
  non-UTF-8 paths.
- OSC 7 pwd, embedded surface cwd/command/env/initial input,
  ghostty_surface_text and GTK file drops keep raw bytes.
- XTVERSION, TERM_PROGRAM_VERSION, the About dialog and crash metadata
  use ghostty_build_info instead of hardcoded versions.

Test Plan:
- cargo test --workspace (3327 passed)
- cargo clippy --workspace --all-targets -- -D warnings

crates/ghostty-lib/Cargo.toml

@@ -23,6 +23,7 @@ ghostty-bench.workspace = true
 ghostty-cli.workspace = true
 ghostty-config.workspace = true
 ghostty-core.workspace = true
+ghostty-crash.workspace = true
 ghostty-input.workspace = true
 ghostty-inspector.workspace = true
 ghostty-os.workspace = true
@@ -31,6 +32,9 @@ ghostty-terminal.workspace = true
 ghostty-vt.workspace = true
 log = "0.4.34"
 
+[target.'cfg(unix)'.dependencies]
+libc = "0.2.190"
+
 [target.'cfg(target_vendor = "apple")'.dependencies]
 block2 = "0.6.2"
 dispatch2 = "0.3.1"
@@ -40,6 +44,7 @@ objc2-foundation = "0.3.2"
 objc2-metal = { version = "0.3.2", features = ["block2"] }
 
 [dev-dependencies]
+ghostty-build-info.workspace = true
 tempfile = "3"
 
 # The workspace forbids `unsafe`; this crate is the C ABI boundary, so it