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-apprt/src/runtime_api.rs

@@ -198,17 +198,13 @@ pub trait CoreSurface {
     fn complete_clipboard_request(
         &self,
         req: ClipboardRequest,
-        data: &str,
+        data: &[u8],
         confirmed: bool,
     ) -> Result<(), ClipboardError>;
     /// [`CoreSurface::complete_clipboard_request`] for a paste of raw bytes
-    /// (Zig data is `[]const u8`). The default converts lossily.
+    /// (Zig data is `[]const u8`).
     fn complete_paste_bytes(&self, data: &[u8], confirmed: bool) -> Result<(), ClipboardError> {
-        self.complete_clipboard_request(
-            ClipboardRequest::Paste,
-            &String::from_utf8_lossy(data),
-            confirmed,
-        )
+        self.complete_clipboard_request(ClipboardRequest::Paste, data, confirmed)
     }
     /// After the user confirms (`surface.config.clipboard_read = .allow`).
     fn set_clipboard_read_allowed(&self, allow: bool);