Multi message conversation support

[yashg4509]

Models can now reference previous messages in a conversation.

What changed

• New context.py: Handles conversation history with smart summarization (keeps recent messages, summarizes old ones)
• Updated council flow: Stage 1 gets full context, Stages 2 & 3 stay focused on current responses
• Frontend: Input form always visible now, shows context indicator for long conversations

How it works

Short conversations: pass everything verbatim
Long conversations: summarize older messages + keep last 5 exchanges

Stage 1 models see full history → Stage 2 ranks objectively → Stage 3 synthesizes

Notes

• Backward compatible with existing chats
• Context kicks in automatically on next message