feat(text-injection): speed up ydotool injection with explicit --key-delay (#488)

Pass --key-delay 8 to ydotool type instead of relying on the default
(12-20ms). This makes text injection ~3x faster while keeping key-delay
above zero to avoid the Shift-leak bug where capital letters corrupt
following characters.

The delay is configurable via VOCALINUX_YDOTOOL_KEY_DELAY env var.

Note: --key-hold flag from the original issue does not exist in standard
ydotool (verified against official man page and v1.0.4 source).

Fixes #482

src/vocalinux/text_injection/text_injector.py

@@ -987,7 +987,13 @@ class TextInjector:
         if self.wayland_tool == "wtype":
             cmd = ["wtype", text]
         else:  # ydotool
-            cmd = ["ydotool", "type", text]
+            # Pass explicit timing parameters to speed up injection.
+            # ydotool defaults to --key-delay 12 (or 20 in older versions).
+            # We use a faster default configurable via environment variable.
+            # IMPORTANT: key-delay must stay > 0 to avoid Shift-leak bug where
+            # capital letters corrupt following characters (e.g. "Can you" -> "CAN YOu").
+            key_delay = os.environ.get("VOCALINUX_YDOTOOL_KEY_DELAY", "8")
+            cmd = ["ydotool", "type", "--key-delay", key_delay, text]
 
         try:
             subprocess.run(cmd, check=True, stderr=subprocess.PIPE, text=True)