fix(guardrails): enable hard_stop_enabled by default

[zccyman]

Problem

tool_loop_guardrails.hard_stop_enabled defaults to false. Guardrails detect retry loops (same failing command, same tool failure, idempotent no-progress) and inject warning text, but models frequently ignore text guidance and continue retrying until max_iterations (90). A single terminal failure loop can consume 90+ API calls doing nothing useful.

Fix

Change default from false → true in two locations:

1. ToolCallGuardrailConfig.hard_stop_enabled dataclass default
2. hermes_cli/config.py default config dict

Users who prefer unlimited retries can opt out via:

tool_loop_guardrails:
  hard_stop_enabled: false

Validation

Updated 3 existing tests that assumed hard_stop_enabled=False to explicitly pass hard_stop_enabled=False. Updated 1 test that asserted the default value. All 13 guardrail tests pass.

Closes #25823

[teknium1]

Thanks for the focused guardrail coverage. Current main still has the warning-only default, so the underlying retry-cost report is real.

Problems

• The global flip conflicts with the current documented design for interactive sessions: website/docs/user-guide/configuration.md:1344-1362 says warning-only is intentional for CLI/TUI and hard stops are an explicit unattended-deployment setting. agent/tool_guardrails.py:65-73 and hermes_cli/config.py:1394-1399 implement that same contract.
• The diff changes that contract without updating website/docs/user-guide/configuration.md:1344-1362 or website/docs/user-guide/docker.md:73-82.
• The updated tests cover the dataclass default, but not the production load_config() → agent/agent_init.py:1307-1318 path or an explicit false opt-out.

Suggested changes

• Resolve the global-versus-platform-specific behavior decision before salvage; related PR #49189 describes the platform-aware alternative.
• If the global default is chosen, update both docs and add configuration-to-runtime coverage.

This is an automated hermes-sweeper review.

[teknium1]

This changes the documented interactive-session contract globally. Current main explicitly preserves warning-only CLI/TUI behavior and requires an opt-in for unattended deployments (website/docs/user-guide/configuration.md:1344-1362); please resolve that product decision and update the corresponding docs before changing this default.