fix: systematic byte fidelity for config strings and RV7 gaps

Resolves the 9 gap groups in docs/rewrite/notes/review-rv7-codex.md and
audits every string-typed config field against its consumers
(field -> consumers -> decode status table in final-Z9.md):
- Windows EnvMap keys use a port of Zig's nls.zig uppercase table
  (upcaseW); Windows locale init follows Zig's chain (setlocale +
  _putenv_s); malformed WTF-8 now fails process launch conversions like
  Zig instead of substituting U+FFFD; kitty file paths convert WTF-8.
- bash --rcfile/--init-file, configured TERM and inherited GTK LANG
  keep their original bytes.
- C API clipboard completion and ghostty_surface_binding_action take
  bytes; complete_clipboard_request is byte-typed through the core.
- text:/csi:/esc: bindings, enquiry-response, input = path:, embedded
  initial_input, search needles, titles, link regexes, clipboard
  codepoint map, command palette text and GTK font/namespace values
  decode the escape encoding before use.

Remaining by design: D-Bus a{ss} values and +new-window arguments are
UTF-8 by D-Bus type. C API key/preedit text follows separately.

Test Plan:
- cargo test --workspace
- just check-macos (both), just check-windows, just check-wasm

crates/ghostty-termio/src/shell_integration.rs

@@ -263,7 +263,9 @@ fn setup_bash(
 
     env.insert("GHOSTTY_BASH_INJECT", inject);
     if let Some(v) = rcfile {
-        env.insert("GHOSTTY_BASH_RCFILE", v);
+        // The intercepted argument is an encoded OS string; the env var gets
+        // its original bytes (Zig inserts the argument slice unchanged).
+        env.insert("GHOSTTY_BASH_RCFILE", EncodedOs::from_encoded(v).to_os());
     }
 
     // In POSIX mode, HISTFILE defaults to ~/.sh_history, so unless we're
@@ -671,6 +673,24 @@ mod tests {
         );
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn bash_rcfile_keeps_original_bytes() {
+        use std::os::unix::ffi::OsStrExt;
+
+        let res = TmpResourcesDir::new(Shell::Bash);
+        for raw in [&b"/home/x/\xffrc"[..], "/home/x/\u{fdd0}rc".as_bytes()] {
+            let mut env = EnvMap::new();
+            let command = Command::Direct(vec![
+                "bash".to_owned(),
+                "--rcfile".to_owned(),
+                EncodedOs::from_bytes(raw).into_encoded(),
+            ]);
+            setup_bash(&command, &res.enc(), &mut env).unwrap();
+            assert_eq!(env.get("GHOSTTY_BASH_RCFILE").unwrap().as_bytes(), raw);
+        }
+    }
+
     #[test]
     fn bash_histfile() {
         let res = TmpResourcesDir::new(Shell::Bash);