Story 17: Display Context Window Usage with emoji indicator
- Added real-time context window usage indicator in header
- Format: emoji + percentage (🟢 52%)
- Color-coded emoji: 🟢 <75%, 🟡 <90%, 🔴 >=90%
- Hover tooltip shows full details: 'Context: 4,300 / 8,192 tokens (52%)'
- Token estimation: 1 token ≈ 4 characters
- Model-aware context windows: llama3 (8K), qwen2.5 (32K), deepseek (16K)
- Includes system prompts, messages, tool calls, and streaming content
- Updates in real-time as conversation progresses
- All quality checks passing (TypeScript, Biome, Clippy, builds)
Tested and verified:
- Shows accurate percentage of context usage
- Emoji changes color at appropriate thresholds
- Different models show correct context window sizes
- Can exceed 100% when over limit (shows red)
- Tooltip provides exact token counts
bd8d838457