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

**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 #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

Start by reading ROADMAP.md and docs/design/INTERACTIVE_AGENTS.md, then review the schema in INTERACTIVE_AGENTS.md and the bgagent status entry point. Map the event schema, CLI rendering, formatter fanout, and notification filtering before implementing. Done means progress_report events are emitted and routed, status renders the latest report, and the listed schema, CLI, and fanout tests pass.

Written by the indexing model from the issue text.