refactor: align docs and integrations with 0.7 boundaries

[rlippmann]

What changed

• aligned late-0.7 docs and roadmap wording to the current architecture and scope
• simplified jargon in core docs while preserving important technical boundaries
• refactored integration trace/state handling to rely on stabilized 0.7 surfaces (controller/state_diff paths) where practical
• reduced integration pending-state schema peeking in favor of Engine.has_pending_clarification() for boolean runtime gates
• removed OpenWebUI compact-trace fallback duplication and required packaged compact trace helper behavior in the OpenWebUI examples

Why

• make 0.7 release docs more accurate and easier to onboard from without changing semantics
• reduce integration coupling to internal checkpoint/state schema details
• keep integration behavior deterministic while moving examples toward the intended public boundary surfaces

Checklist

• pre-commit run (uv run pre-commit run --all-files)
• tests pass (uv run pytest)