harden skill runtime readiness

[pmbstyle]

Summary

• Add skill verification and enable/disable CLI paths, plus docs for the installed skill workflow.
• Harden skill install/runtime readiness checks, including archive extraction safety, stale runtime env detection, and registry override cleanup.
• Expose generic skill tools in the Octo runtime and preserve requested skill guidance payloads through tool-result rendering.

Why

The skill runtime had drifted since the original implementation: installed skills could be hard to verify, runtime env status could become stale after requirements changed, generic skill tools were discoverable but not active in the initial Octo tool set, and large requested skill guidance could be compacted a second time before reaching the model. Operators also had no first-class way to disable a skill without deleting its files.

Validation

• uv run pytest tests/test_skill_management.py tests/test_cli_skill_install.py tests/test_tool_inventory.py tests/test_router_tool_budget.py -q
• uv run pytest tests/test_tool_payloads.py tests/test_tool_inventory.py tests/test_router_tool_budget.py tests/test_octo_tool_loop.py tests/test_skill_management.py tests/test_agent_worker_contracts.py tests/test_worker_template_security.py -q
• uv run pytest tests/test_skill_runtime_envs.py tests/test_skill_management.py tests/test_skill_installer.py tests/test_cli_skill_install.py tests/test_skill_bundles.py tests/test_agent_worker_contracts.py tests/test_worker_template_security.py tests/test_tool_inventory.py -q
• uv run ruff check src/octopal/tools/skills/management.py src/octopal/cli/main.py tests/test_skill_management.py tests/test_cli_skill_install.py
• uv run ruff check src/octopal/runtime/tool_payloads.py src/octopal/runtime/octo/router.py src/octopal/tools/inventory.py tests/test_tool_payloads.py tests/test_router_tool_budget.py tests/test_tool_inventory.py
• uv run octopal skill --help
• git diff --check