fix: copy_title_to_clipboard respects user-overridden title (#10694)

## Summary
- Fixes #10345 — `copy_title_to_clipboard` now copies the user-set
custom title instead of the raw terminal title
- Adds a new `copy_title` apprt action as [suggested by
@mitchellh](https://github.com/ghostty-org/ghostty/issues/10345#issuecomment-2601002974)
- Each platform (GTK + macOS) resolves the effective title (user
override → terminal title fallback) before copying to clipboard

## Changes
- **`src/apprt/action.zig`** — New `copy_title` void action
- **`include/ghostty.h`** — C ABI enum entry
- **`src/Surface.zig`** — Binding handler now dispatches apprt action
instead of inline logic
- **`src/apprt/gtk/class/surface.zig`** — `getEffectiveTitle()` helper
(returns `title_override orelse title`)
- **`src/apprt/gtk/class/application.zig`** — GTK action handler
- **`macos/.../Ghostty.App.swift`** — macOS handler using
`surfaceView.title` + `NSPasteboard`

*Note*: This PR was *AI* assisted.

src/apprt/action.zig

@@ -330,6 +330,11 @@ pub const Action = union(Key) {
     /// The readonly state of the surface has changed.
     readonly: Readonly,
 
+    /// Copy the effective title of the surface to the clipboard.
+    /// The effective title is the user-overridden title if set,
+    /// otherwise the terminal-set title.
+    copy_title_to_clipboard,
+
     /// Sync with: ghostty_action_tag_e
     pub const Key = enum(c_int) {
         quit,
@@ -395,6 +400,7 @@ pub const Action = union(Key) {
         search_total,
         search_selected,
         readonly,
+        copy_title_to_clipboard,
     };
 
     /// Sync with: ghostty_action_u

src/apprt/gtk/class/application.zig

@@ -674,6 +674,8 @@ pub const Application = extern struct {
             .close_tab => return Action.closeTab(target, value),
             .close_window => return Action.closeWindow(target),
 
+            .copy_title_to_clipboard => return Action.copyTitleToClipboard(target),
+
             .config_change => try Action.configChange(
                 self,
                 target,
@@ -1921,6 +1923,13 @@ const Action = struct {
         }
     }
 
+    pub fn copyTitleToClipboard(target: apprt.Target) bool {
+        return switch (target) {
+            .app => false,
+            .surface => |v| v.rt_surface.gobj().copyTitleToClipboard(),
+        };
+    }
+
     pub fn configChange(
         self: *Application,
         target: apprt.Target,

src/apprt/gtk/class/surface.zig

@@ -1989,6 +1989,24 @@ pub const Surface = extern struct {
         return self.private().title;
     }
 
+    /// Returns the effective title: the user-overridden title if set,
+    /// otherwise the terminal-set title.
+    pub fn getEffectiveTitle(self: *Self) ?[:0]const u8 {
+        const priv = self.private();
+        return priv.title_override orelse priv.title;
+    }
+
+    /// Copies the effective title to the clipboard.
+    pub fn copyTitleToClipboard(self: *Self) bool {
+        const title = self.getEffectiveTitle() orelse return false;
+        if (title.len == 0) return false;
+        self.setClipboard(.standard, &.{.{
+            .mime = "text/plain",
+            .data = title,
+        }}, false);
+        return true;
+    }
+
     /// Set the title for this surface, copies the value. This should always
     /// be the title as set by the terminal program, not any manually set
     /// title. For manually set titles see `setTitleOverride`.