terminal: add semi-colon character to word boundary list for easier selection (#9069)

Sorry, I'm living dangerously here and haven't started a discussion.

New ghostty user. When working interactively with SQL clients you're
often writing semi-colons at the end of statements, e.g. `select * from
table;`

It's super annoying when you double-click to select the word `table` it
actually selects `table;` Anecdotally, this behaviour disagrees with
other terminals I've tried (tho not exhaustive).

Disclosure: Claude wrote this code but, ironically, I "assisted it" by
pointing to the file and function after uncovering issue #30 and
relevant PR.

src/terminal/Screen.zig

@@ -2559,6 +2559,7 @@ pub fn selectWord(self: *Screen, pin: Pin) ?Selection {
         '`',
         '|',
         ':',
+        ';',
         ',',
         '(',
         ')',
@@ -7813,6 +7814,7 @@ test "Screen: selectWord with character boundary" {
         " `abc` \n123",
         " |abc| \n123",
         " :abc: \n123",
+        " ;abc; \n123",
         " ,abc, \n123",
         " (abc( \n123",
         " )abc) \n123",