…ents

implement RAG chatbot features with search, UI improvements, and tests

- Add Inter font via Google Fonts for crisper typography
- Switch accent color to indigo/purple gradient (#6366f1 → #8b5cf6)
- Add branded sidebar header with gradient logo icon
- Redesign New Chat button with + icon and indigo pill style
- Apply gradient to user message bubbles with glow shadow
- Add subtle dot-grid background texture to chat area
- Polish send button with gradient, hover lift, and glow
- Restyle input focus with indigo border and focus ring
- Improve loading dots to pulse with primary color
- Slim scrollbars to 4px for cleaner look

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

- Fix .gitignore: replace *.env with .env and .env.* (too broad)
- Define SourceItem Pydantic model in app.py for typed sources (replaces List[Any])
- Move import json to top of vector_store.py (was inside method)
- Add trailing newlines to ai_generator.py and vector_store.py
- Register CourseOutlineTool in conftest.py tool_manager fixture
- Add test_outline_tool.py with full coverage for CourseOutlineTool
- Add console.warn in startNewChat() instead of silently swallowing errors

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