Documentation: the stop gate blocks on a node the work item never entered

The ready-to-ship gate's documentation item: the affected capability docs are updated in the same pull request as the change.

Capability docs

docs/capabilities/process-graph.md owns the graph runtime, check, and the harness gate's contract.

• A new requirement under State, recovery and the escape hatch: the stop gate SHALL NOT ask about a node the work item never entered. It covers:
  • pointer on every report;
  • the walk to the pointer;
  • the inconclusive rules;
  • the accepted residual;
  • the state: line.
• A history row for issue-429, above issue-343.

docs/capabilities/cli.md: check's requirement says the report keeps the pointer under --recompute, and that the state: line names it when it differs.

Documentation

• docs/cli/commands/check.md: the --recompute section explains the derived position, shows the new state: line, and says why the stop gate reads both positions. The JSON paragraph lists pointer.
• skills/the-loop/reference/automation.md: the Stop gate asks about the node the item is at, never one it has not entered.
• POST /graph/check (route docstring and docs/api-specs/openapi/the-loop.v1.yaml) and the check_work_item MCP tool describe pointer.

Not affected

• docs/capabilities/distribution.md: the gate is still declared the same way in hooks/hooks.json.
• docs/capabilities/control-plane.md: no route or parameter changed, only a response key.