fix: close remaining gaps found by the completeness audit

Addresses the partial ports listed in
docs/rewrite/notes/review-completeness-codex.md (details in
docs/rewrite/notes/gaps-X2.md):
- Flatpak: the exit watcher no longer consumes the host command; a
  shared FlatpakSignalHandle lets closing a surface still SIGHUP the
  host process group.
- Child environment is byte-preserving end to end (ghostty_os::EnvMap
  of OsStrings) and Snap paths are filtered like filterSnapPaths.
- argv handling no longer panics on non-UTF-8 arguments.
- URI percent-decoding keeps raw bytes; OSC 7 pwd is passed through
  without lossy conversion.
- Keybinding comparison/hashing uses full Unicode case folding from a
  table generated from CaseFolding.txt (Unicode 17.0.0).
- Link regexes set Oniguruma's whole-search retry limit through the new
  minimal ghostty-onig crate (one SAFETY-commented FFI call).
- OSC 9 NUL-capacity check ordering matches Zig.
- Wayland registry binds/clears globals advertised after startup.
- Custom shaders may pass sampler2D to helper functions (naga adapter).
- +list-themes preview renders OSC 8 links, styled underlines and
  follows color-scheme reports.

Also includes the inspector's integration edits in shared files
(renderer state hook, termio VT recording, core/apprt-gtk wiring), X1's
config/input/cli additions for completion generation, and a fix for a
race in the termio backpressure test (it wrote before `stty raw`
applied, so the cooked line discipline dropped bytes past MAX_CANON).

Test Plan:
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings

crates/ghostty-core/src/surface/mod.rs

@@ -37,6 +37,7 @@
 pub mod binding;
 pub mod clipboard;
 pub mod config;
+pub mod inspector;
 pub mod keyboard;
 pub mod mouse;
 
@@ -251,6 +252,9 @@ pub struct Surface {
     /// Used to rate limit BEL handling.
     last_bell_time: Cell<Option<Instant>>,
 
+    /// The terminal inspector, if active (Zig: `inspector: ?*Inspector`).
+    pub(crate) inspector: RefCell<Option<Arc<ghostty_inspector::Shared>>>,
+
     /// Debug screenshot state (see `debug_screenshot`).
     created: Instant,
     debug_shot_done: Cell<bool>,
@@ -474,6 +478,7 @@ impl Surface {
             command_timer: Cell::new(None),
             search: RefCell::new(None),
             last_bell_time: Cell::new(None),
+            inspector: RefCell::new(None),
             created: Instant::now(),
             debug_shot_done: Cell::new(false),
         });
@@ -1798,7 +1803,7 @@ impl Drop for Surface {
 /// (`rt_surface.defaultTermioEnv()`, which already removed the variables it
 /// does not want to leak); only if it provides nothing (the Zig error path)
 /// do we fall back to the process environment (`getEnvMap`).
-fn rt_surface_env(rt: &dyn RtSurface) -> std::collections::HashMap<String, String> {
+fn rt_surface_env(rt: &dyn RtSurface) -> ghostty_os::EnvMap {
     let rt_env = rt.default_termio_env();
     if rt_env.is_empty() {
         return ghostty_os::env::get_env_map();
@@ -1960,4 +1965,16 @@ impl CoreSurface for Surface {
             ydpi: s.ydpi,
         }
     }
+
+    fn activate_inspector(&self) -> Result<(), CoreError> {
+        Surface::activate_inspector(self)
+    }
+
+    fn deactivate_inspector(&self) {
+        Surface::deactivate_inspector(self);
+    }
+
+    fn render_inspector(&self, ui: &ghostty_inspector::imgui::Ui) {
+        Surface::render_inspector(self, ui);
+    }
 }