Deepen meeting prompt synthetic coverage

[r3dbars]

Summary:

• Add deterministic no-spam cases for pending calendar prompts, pending app-only prompts, dismissed calendar cooldowns, and expired cooldown recovery.
• Cover active recording and existing detected-popup gates when valid calendar/app signals are present.
• Add Zoom native plus browser WebRTC calendar-route cases that prove combined evidence stays one pending calendar prompt.

Tests:

• bash scripts/dev/agent-preflight.sh
• bash build-deps.sh --force (needed after stale deps gate)
• bash build.sh --no-open
• bash run-tests.sh --filter SyntheticMeetingPromptTests (53/53 after rebase)
• bash run-tests.sh (5319/5319 after rebase)
• /Users/redbars/.codex/skills/codex-review/scripts/codex-review --mode auto (clean: no accepted/actionable findings reported)