Move color strip sources from Targets tab to Sources tab

- Remove csColorStrips CardSection from targets.js, add to streams.js
- Add color_strip sub-tab with tree nav entry between Picture and Audio
- Update navigateToCard refs in target cards and command palette
- Update tutorial steps: remove led-css from targets, add color_strip to sources
- Add i18n keys for streams.group.color_strip and tour.src.color_strip

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/locales/en.json

@@ -355,6 +355,7 @@
   "tour.src.templates": "Capture Templates — reusable capture configurations (resolution, FPS, crop).",
   "tour.src.static": "Static Image — test your setup with image files instead of live capture.",
   "tour.src.processed": "Processed — apply post-processing effects like blur, brightness, or color correction.",
+  "tour.src.color_strip": "Color Strips — define how screen regions map to LED segments.",
   "tour.src.audio": "Audio — analyze microphone or system audio for reactive LED effects.",
   "tour.src.value": "Value — numeric data sources used as conditions in automations.",
   "tour.src.sync": "Sync Clocks — shared timers that synchronize animations across multiple sources.",
@@ -416,6 +417,7 @@
   "streams.description": "Sources define the capture pipeline. A raw source captures from a display using a capture template. A processed source applies postprocessing to another source. Assign sources to devices.",
   "streams.group.raw": "Screen Capture",
   "streams.group.processed": "Processed",
+  "streams.group.color_strip": "Color Strips",
   "streams.group.audio": "Audio",
   "streams.section.streams": "Sources",
   "streams.add": "Add Source",