feat(ux): smart progress updates (manager-style status)

[krokoko]

Context: ROADMAP.md → Smart progress updates

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Component

Agent (Python runtime)

Describe the feature

Structured agent-emitted progress events in TaskEventsTable: done, next, decisions, blockers—human-readable manager-style status surfaced via bgagent status, GitHub/Slack/email dispatchers, and future control panel.

Use case

Raw watch/events streams are noisy. Operators want a consistent summary without waking the agent or hallucinating via LLM.

Proposed solution

1. Agent hook emits progress_report events on turn boundaries (schema in INTERACTIVE_AGENTS.md).
2. bgagent status renders latest report + deterministic ops fields.
3. Slack/GitHub formatters for report blocks (pairs with Add Slack-button approvals for Cedar HITL approval gates #112 polish).
4. Notification channel filters include progress_report.
5. Tests: event schema, CLI rendering, fanout routing.

Other information

• Complements bgagent ask for on-demand Q&A.

• Design context: docs/design/INTERACTIVE_AGENTS.md.

• This might be a breaking change

[krokoko]

Parent epic: #438