Add public social account guard scenario

[kriptoburak]

Summary

• Add a public_social_account_actions risk-rule category for risky social account automation.
• Add a TweetClaw/OpenClaw Risk Test example and classifier path for fake giveaway posts, replies, follower export, and DMs without confirmation.
• Add docs/social-account-guard.md and link it from the Guard section so users can run the scenario without live credentials.

Validation

• git diff --cached --check
• uv run --python 3.11 --extra dev pytest tests/test_risk_test_service.py tests/test_guard_risk_rules.py -q - 14 passed
• Edited-file link sweep: new GitHub/OpenClaw links returned 200; npm view @xquik/tweetclaw version dist.tarball repository.url homepage --json confirmed 1.6.31; npm package page returned a 403 bot-protection response; pre-existing commented README image assets/comon_option.png is missing.
• uv run --python 3.11 --extra dev pytest tests -q currently has 160 passed and 11 unrelated failures in guard model token expectations, nanobot stream/session behavior, and system-status path handling.

No live social accounts, credentials, or write actions were used.