feat: i18n full support, responsive UI, multi-model AI config, and bug fixes

Major Features:
- Internationalization (i18n) with auto-detection for ES/EN/PT
- Mobile-first responsive design for Studio and Experience
- Multi-model AI configuration (llama3.2:3b, qwen3.5:9b, gpt-oss:latest)
- Course language configuration (auto-detect or fixed per course)

Backend Changes:
- shared/common: ModelType enum for intelligent model selection
- LMS: log_ai_usage function migration (fix chat tutor 500 error)
- LMS/CMS: course language config fields (language_setting, fixed_language)
- LMS: /courses/{id}/language-config endpoint for language detection

Frontend Changes:
- Experience: Enhanced i18n with browser language detection
- Experience: Audio recording with HTTPS check and error handling
- Studio: Memory game with unique pair IDs and debug logging
- Studio: Expanded translations (250+ keys for ES, EN, PT)
- Both: Language selector in headers (mobile responsive)

Documentation:
- AI_MODELS_CONFIG.md: Multi-model configuration guide
- RESPONSIVIDAD_GUIA.md: Mobile-first design patterns
- I18N_RESPONSIVIDAD_IMPLEMENTACION.md: Implementation details
- DEBUG_AUDIO_RECORDING.md: Audio troubleshooting guide
- DEBUG_MEMORY_GAME.md: Memory game debugging steps

Bug Fixes:
- Fix chat tutor 500 error (missing log_ai_usage function)
- Fix audio recording (HTTPS check, browser compatibility)
- Fix memory game pair IDs (unique ID generation)
- Fix HotspotBlock TypeScript errors

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

services/lms-service/migrations/20260320000002_add_course_language_config.sql

@@ -0,0 +1,24 @@
+-- Add language configuration to courses table (LMS side)
+-- This mirrors the CMS migration for cross-service compatibility
+
+ALTER TABLE courses 
+ADD COLUMN IF NOT EXISTS language_setting VARCHAR(20) DEFAULT 'auto',
+ADD COLUMN IF NOT EXISTS fixed_language VARCHAR(5) DEFAULT NULL;
+
+-- Add comment explaining the fields
+COMMENT ON COLUMN courses.language_setting IS 'Language mode: auto (detect from user browser) or fixed (use fixed_language)';
+COMMENT ON COLUMN courses.fixed_language IS 'Fixed language code (es, en, pt) when language_setting is fixed. NULL when language_setting is auto.';
+
+-- Add check constraints (only if they don't exist)
+DO $$ BEGIN
+    ALTER TABLE courses ADD CONSTRAINT chk_language_setting CHECK (language_setting IN ('auto', 'fixed'));
+EXCEPTION WHEN duplicate_object THEN null;
+END $$;
+
+DO $$ BEGIN
+    ALTER TABLE courses ADD CONSTRAINT chk_fixed_language CHECK (fixed_language IS NULL OR fixed_language IN ('es', 'en', 'pt'));
+EXCEPTION WHEN duplicate_object THEN null;
+END $$;
+
+-- Create index for filtering courses by language
+CREATE INDEX IF NOT EXISTS idx_courses_language ON courses(language_setting, fixed_language);