Tasks: change the default session-control comment keywords

Phase 3 of 3. Derived from requirements.md and design.md (both locked). tdd.mode: standard — the test files are updated alongside the value they assert, since this is a pure default-value change with no new behaviour to red/green.

Dependency graph (DAG)

flowchart LR
    T1["T1 runtime default<br/>control.py"] --> T2["T2 config mirrors<br/>yaml + schema + template"]
    T1 --> T3["T3 unit tests<br/>test_control.py"]
    T1 --> T4["T4 integration test<br/>constants"]
    T2 --> T5["T5 docs"]
    T3 --> T6["T6 make check"]
    T4 --> T6
    T5 --> T6
    T6 --> T7["T7 capability doc<br/>+ CHANGELOG + execution log"]
    T7 --> T8["T8 ready-to-ship gate"]

Task list

• [x] T1 — Runtime default. cli/the_loop/control.py: DEFAULT_KEYWORDS → the-loop start/stop/pause/resume; update the module docstring's two boundary-regex examples to match. Requirements: 1.1, 1.3.
• [x] T2 — Config mirrors. .the-loop/cli-config.yaml, skills/the-loop/templates/cli-config.yaml, .the-loop/cli-config.schema.json (keywords.*.default). Requirements: 1.2.
• [x] T3 — Unit tests. cli/tests/test_control.py: default assertions + reshape the boundary-violation parametrization per design.md §4. Requirements: 3.1.
• [x] T4 — Integration test constants. cli/tests/test_control_integration.py, cli/tests/test_poller.py: update the four/two *_KEYWORD module constants. Requirements: 3.2.
• [x] T5 — Docs. docs/config/cli/routing-options.md, docs/capabilities/webhook-triggers.md (current-behaviour prose), docs/cli/concepts.md, docs/cli/getting-started.md (prose + diagram label), docs/cli/commands/sessions.md, cli/README.md, skills/the-loop/reference/automation.md, commands/upgrade-the-loop.md. Historical specs/decisions/changelog entries left untouched. Requirements: 2.1, 2.2.
• [x] T6 — make check. ruff, ruff format, pyright, markdownlint, config validation, pytest (full cli/ suite) green. Requirements: 3.3.
• [x] T7 — Capability doc + execution log. New history row in docs/capabilities/webhook-triggers.md; keep execution-log.md current. CHANGELOG.md is CI-generated (never hand-edited) — the implementing commit carries the BREAKING CHANGE: footer instead (Requirement 2.3). No new decision doc: the value changes, not the decision-040 trust boundary. Requirements: 2.3.
• [x] T8 — Ready-to-ship gate. Security checklist recorded (no new surface); reviewer briefing posted on the PR. Requirements: all.