Sync pattern shortnames with LED bar firmware

- Add 'on' and 'off' pattern mappings to match LED bar
- Document that PATTERN_NAMES must match led-bar/src/patterns.py
- Keep backend-specific patterns (sequential_pulse, alternating_phase) separate
- Ensures frontend can use the same pattern names as LED bar expects

src/control_server.py

@@ -31,7 +31,10 @@ SOUND_CONTROL_HOST = os.getenv("SOUND_CONTROL_HOST", "127.0.0.1")
 SOUND_CONTROL_PORT = int(os.getenv("SOUND_CONTROL_PORT", "65433"))
 
 # Pattern name mapping for shorter JSON payloads
+# These must match the shortnames defined in led-bar/src/patterns.py
 PATTERN_NAMES = {
+    "on": "on",
+    "off": "o",
     "flicker": "f",
     "fill_range": "fr", 
     "n_chase": "nc",
@@ -40,9 +43,10 @@ PATTERN_NAMES = {
     "rainbow": "r",
     "specto": "s",
     "radiate": "rd",
+    "segmented_movement": "sm",
+    # Backend-specific patterns (not sent to LED bars)
     "sequential_pulse": "sp",
     "alternating_phase": "ap",
-    "segmented_movement": "sm",
 }