Trim bootstrap text and derive its inputs from the agent context

Text:
- Drop "ack immediately" rule: the MESSAGES section already covers
  responding, and an immediate "on it" wakes the requester and cancels
  its went-idle-without-responding watch.
- Spawn line teaches --hcom-prompt instead of --terminal.
- Add "Launched by: @x" when another agent launched this one.
- Remove stale/filler bits: Task background=true, subagent hello
  announce, subagent ack rule, "Substitute in examples".

Code:
- get_bootstrap(db, ctx, name, tool) derives tag, relay, notes, headless
  and launcher itself instead of 11 positional args across 12 callers.
- Fix Claude never getting the relay notice (hardcoded false).
- Tag comes from the instance row only; the config-tag fallback told
  untagged adhoc agents to message an @tag- group they aren't in.
- Auto delivery applies to any launched integration instead of a
  hand-kept tool list.
- Active snapshot skips subagent rows and inactive agents and reports
  overflow.