Optimize agenda drafts for audience demand

[EllAchE]

Summary

• Conference drafts now separate talks with overlapping likely audiences and fit demand to room capacity instead of filling only the earliest free slots.
• Organizers can record expected attendance and speaker popularity, tune six event-level weights, rebuild drafts, and see the rationale for each proposed placement.
• Room, track, and speaker conflicts remain hard constraints, and every placement still requires organizer review before it changes the agenda.

Test plan

• Evaluated overlapping software topics, unrelated parallel content, stage sizing, hard speaker conflicts, venue flow, weight changes, and deterministic output.
• Verified weight bounds and the additive, non-destructive migration shape.
• Parsed every changed TypeScript and TSX entry point with Bun's bundler.
• Ran git diff --check and verified every branch commit contains a signature.
• GitHub CI: lint, build, Vitest, migration-backed integration tests.

Review notes

• Apply additive migration 0021_hot_xorn before deploying code that reads the new columns. No database migration was run from this branch.
• This PR includes the approved two-line quoting repair in lib/ai/notice.ts for a syntax error inherited from main.
• Browser evidence was not captured. This worktree has no installed dependencies, installation was not authorized, and the Playwright preflight was blocked because it may install tooling. The UI paths were syntax-checked locally and the dependency-backed build and tests passed in CI.

Part of S-134474

Agent Audit

• Action: create-pr
• Timestamp: 2026-08-16T21:20:02Z
• Agent: codex
• Agent type: codex
• Triggered by: loganharless
• Origin: loganharless@MacBook-Pro-5
• Session: 01a00c30-215e-7593-8388-e47fd987bf31
• Source repo: EllAchE/sessionboard-oss
• Worktree: /Users/loganharless/Desktop/da/worktrees/cicero-s-134474-intelligent-agenda-20260816-162220
• Branch: s-134474-intelligent-agenda-20260816-162220
• Head commit: 6848542
• tmux pane: %336
• tmux session: resume-triage-gmail-inbox