fix(ansible): auto-detect WSL2 and set correct ai_stack_host per deployment (#3503)

[mrveiss]

Summary

• Adds WSL2 detection in the backend Ansible role by reading /proc/version on each target host at deploy time
• If the host is WSL2 (contains microsoft) and backend_ai_stack_host is still the default 127.0.0.1, overrides it to 10.255.255.254 (WSL2 mirrored networking loopback IP)
• The when: backend_ai_stack_host == '127.0.0.1' guard preserves any explicit operator override (e.g. pointing at a remote AI stack VM)
• Every subsequent reprovisioning run will now produce a correct AUTOBOT_AI_STACK_HOST in the env file without any manual intervention

Closes #3503

Test plan

• Deploy to a WSL2 backend host — verify AUTOBOT_AI_STACK_HOST=10.255.255.254 in /etc/autobot/autobot-backend.env
• Deploy to a native Linux host — verify AUTOBOT_AI_STACK_HOST=127.0.0.1 (unchanged)
• Deploy with backend_ai_stack_host explicitly set in inventory — verify override is not clobbered

🤖 Generated with Claude Code

[github-actions]

✅ SSOT Configuration Compliance: Passing

🎉 No hardcoded values detected that have SSOT config equivalents!

[mrveiss]

Code review complete. No issues found in the PR changes.

Review findings

Variables and defaults: backend_ai_stack_host and backend_ai_stack_port are both defined in roles/backend/defaults/main.yml (the same bug caught in PR #3513 — missing defaults — does not apply here). The template uses them without | default() guards, which is consistent with every other role-variable usage in backend.env.j2 and safe given the defaults.

WSL2 detection logic: The /proc/version slurp + b64decode | lower | search('microsoft') chain is correct and idiomatic Ansible. failed_when: false ensures graceful degradation on non-Linux hosts. The backend_ai_stack_host == '127.0.0.1' guard correctly preserves any explicit operator override.

Task ordering: The WSL2 detection tasks (lines 35–50 of tasks/main.yml) execute before the env template deployment task (line 64), so the overridden value is in scope when backend.env.j2 is rendered.

CI failure: The code-quality check fails on 20 Python files that this PR did not touch (analytics_code_generation_test.py, hooks.py, standardized_agent.py, etc.). This is pre-existing Black formatting drift on the base branch, not introduced by this PR. The PR changes only Ansible YAML files.

Conclusion: Fix is complete and correct. Merging.