Support OSC133 click_events Kitty extension (supported by Fish) (#10536)

This adds support for the `OSC 133 A click_events=1` extension
introduced by Kitty and supported by Fish.[^1]

**What this means:** If the shell advertises `click_events=1` support,
Ghostty will _unconditionally_ (no modifier required) send mouse events
to the shell for clicks on a prompt line, delegating to the supporting
shell to move the cursor as needed. For Fish 4.1+ this means that
clicking on the prompt line moves the cursor (see demo video below).

This PR also contains:

* A minor fix in `cl` parsing but we don't yet implement the logic there
* Updated inspector to show the semantic prompt click mode

## Demo


https://github.com/user-attachments/assets/03ef8975-7ad9-441f-aaa2-9d0eb5c5e36d

## Implementation Details

`click_events` is wildly underspecified, so here are the details the
best I understand them. This itself is not a specification (I omit
details) but adds some more context to it.

The `click_events=1` option can be specified with `OSC 133 A` (Ghostty
also allows it on OSC 133 N). When that is specified, it flags for all
future prompts that the screen supports click events for semantic
prompts. If both `click_events` and `cl` are specified, `click_events`
takes priority if true. If `click_events=0` (disable), then any set `cl`
will take priority.

When a mouse click comes in, we check for the following conditions:

1. The screen supports click events
2. The screen cursor is currently at a prompt
3. The mouse click was at or below the starting prompt line of the
current prompt

If those are met, we encode an SGR mouse event with: left button, press,
coordinates of click. It is up to the shell after that to handle it. Out
of prompt bounds SGR events are possible (specifically below). The shell
should robustly handle this.

[^1]: I don't know any other terminal or shell that supports it at the
moment.

src/shell-integration/fish/vendor_conf.d/ghostty-shell-integration.fish

@@ -51,6 +51,27 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
 
     set --local features (string split , $GHOSTTY_SHELL_FEATURES)
 
+    # Parse the fish version for feature detection.
+    # Default to 0.0 if version is unavailable or malformed.
+    set -l fish_major 0
+    set -l fish_minor 0
+    if set -q version[1]
+        set -l fish_ver (string match -r '(\d+)\.(\d+)' -- $version[1])
+        if set -q fish_ver[2]; and test -n "$fish_ver[2]"
+            set fish_major "$fish_ver[2]"
+        end
+        if set -q fish_ver[3]; and test -n "$fish_ver[3]"
+            set fish_minor "$fish_ver[3]"
+        end
+    end
+
+    # Our OSC133A (prompt start) sequence. If we're using Fish >= 4.1
+    # then it supports click_events so we enable that.
+    set -g __ghostty_prompt_start_mark "\e]133;A\a"
+    if test "$fish_major" -gt 4; or test "$fish_major" -eq 4 -a "$fish_minor" -ge 1
+        set -g __ghostty_prompt_start_mark "\e]133;A;click_events=1\a"
+    end
+
     if contains cursor $features
         # Change the cursor to a beam on prompt.
         function __ghostty_set_cursor_beam --on-event fish_prompt -d "Set cursor shape"
@@ -72,14 +93,14 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
 
     # When using sudo shell integration feature, ensure $TERMINFO is set
     # and `sudo` is not already a function or alias
-    if contains sudo $features; and test -n "$TERMINFO"; and test "file" = (type -t sudo 2> /dev/null; or echo "x")
+    if contains sudo $features; and test -n "$TERMINFO"; and test file = (type -t sudo 2> /dev/null; or echo "x")
         # Wrap `sudo` command to ensure Ghostty terminfo is preserved
         function sudo -d "Wrap sudo to preserve terminfo"
-            set --function sudo_has_sudoedit_flags "no"
+            set --function sudo_has_sudoedit_flags no
             for arg in $argv
                 # Check if argument is '-e' or '--edit' (sudoedit flags)
-                if string match -q -- "-e" "$arg"; or string match -q -- "--edit" "$arg"
-                    set --function sudo_has_sudoedit_flags "yes"
+                if string match -q -- -e "$arg"; or string match -q -- --edit "$arg"
+                    set --function sudo_has_sudoedit_flags yes
                     break
                 end
                 # Check if argument is neither an option nor a key-value pair
@@ -87,7 +108,7 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
                     break
                 end
             end
-            if test "$sudo_has_sudoedit_flags" = "yes"
+            if test "$sudo_has_sudoedit_flags" = yes
                 command sudo $argv
             else
                 command sudo --preserve-env=TERMINFO $argv
@@ -100,7 +121,7 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
     if contains ssh-env $features; or contains ssh-terminfo $features
         function ssh --wraps=ssh --description "SSH wrapper with Ghostty integration"
             set -l features (string split ',' -- "$GHOSTTY_SHELL_FEATURES")
-            set -l ssh_term "xterm-256color"
+            set -l ssh_term xterm-256color
             set -l ssh_opts
 
             # Configure environment variables for remote session
@@ -134,7 +155,7 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
 
                     # Check if terminfo is already cached
                     if test -x "$GHOSTTY_BIN_DIR/ghostty"; and "$GHOSTTY_BIN_DIR/ghostty" +ssh-cache --host="$ssh_target" >/dev/null 2>&1
-                        set ssh_term "xterm-ghostty"
+                        set ssh_term xterm-ghostty
                     else if command -q infocmp
                         set -l ssh_terminfo
                         set -l ssh_cpath_dir
@@ -154,7 +175,7 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
                                 mkdir -p ~/.terminfo 2>/dev/null && tic -x - 2>/dev/null && exit 0
                                 exit 1
                             ' 2>/dev/null
-                                set ssh_term "xterm-ghostty"
+                                set ssh_term xterm-ghostty
                                 set -a ssh_opts -o "ControlPath=$ssh_cpath"
 
                                 # Cache successful installation
@@ -186,7 +207,7 @@ function __ghostty_setup --on-event fish_prompt -d "Setup ghostty integration"
         end
 
         set --global __ghostty_prompt_state prompt-start
-        echo -en "\e]133;A\a"
+        echo -en $__ghostty_prompt_start_mark
     end
 
     function __ghostty_mark_output_start --on-event fish_preexec