feat: add 4 built-in gradients, searchable gradient picker, cleaner modal titles

- Add warm, cool, neon, pastel built-in gradients (promoted from frontend presets)
- Change gradient seeding to add missing built-ins on every startup (not just first run)
- Add searchable option to IconSelect component for filtering by name
- Enable search on gradient, effect palette, and audio palette pickers
- Simplify modal titles: "Add Gradient" / "Edit Gradient" instead of "Add Color Strip Source: Gradient"
- Update INSTALLATION.md and .env.example

server/.env.example

@@ -12,22 +12,9 @@
 # API keys are required. Format: JSON object {"label": "key"}.
 # WLED_AUTH__API_KEYS={"dev": "development-key-change-in-production"}
 
-# ── Storage paths ───────────────────────────────────────
-# All paths are relative to the server working directory.
-# WLED_STORAGE__DEVICES_FILE=data/devices.json
-# WLED_STORAGE__TEMPLATES_FILE=data/capture_templates.json
-# WLED_STORAGE__POSTPROCESSING_TEMPLATES_FILE=data/postprocessing_templates.json
-# WLED_STORAGE__PICTURE_SOURCES_FILE=data/picture_sources.json
-# WLED_STORAGE__OUTPUT_TARGETS_FILE=data/output_targets.json
-# WLED_STORAGE__PATTERN_TEMPLATES_FILE=data/pattern_templates.json
-# WLED_STORAGE__COLOR_STRIP_SOURCES_FILE=data/color_strip_sources.json
-# WLED_STORAGE__AUDIO_SOURCES_FILE=data/audio_sources.json
-# WLED_STORAGE__AUDIO_TEMPLATES_FILE=data/audio_templates.json
-# WLED_STORAGE__VALUE_SOURCES_FILE=data/value_sources.json
-# WLED_STORAGE__AUTOMATIONS_FILE=data/automations.json
-# WLED_STORAGE__SCENE_PRESETS_FILE=data/scene_presets.json
-# WLED_STORAGE__COLOR_STRIP_PROCESSING_TEMPLATES_FILE=data/color_strip_processing_templates.json
-# WLED_STORAGE__SYNC_CLOCKS_FILE=data/sync_clocks.json
+# ── Storage ────────────────────────────────────────────
+# All data is stored in a single SQLite database.
+# WLED_STORAGE__DATABASE_FILE=data/ledgrab.db
 
 # ── MQTT (optional) ────────────────────────────────────
 # WLED_MQTT__ENABLED=false