fix(ansible): deploy.yml standalone redeploy installs python3.12 prerequisite (#3538)

[mrveiss]

Closes #3538

Root cause

deploy.yml lacked the python312 prerequisite step that provision-fleet-roles.yml has. Fresh hosts without Python 3.12 fail when the ai-stack role runs python3.12 -m venv (fixed in PR #3536).

Fix

Added a single task immediately before the AI/ML role block that runs include_role: name: python312 when ai-stack is in the role_list. The python312 role is idempotent — it checks python3.12 --version first and skips installation if already present.

Test plan

• YAML syntax valid
• Standalone redeploy to a fresh host with only Python 3.10 succeeds (python3.12 installed first)
• Idempotent: safe to run on hosts that already have Python 3.12
• Non-ai-stack deploys are unaffected (gated by when: "'ai-stack' in role_list")

[mrveiss]

Code review

Found 1 issue:

1. backend role is excluded from the python312 prerequisite guard — issue bug(ansible): deploy.yml standalone redeploy skips python312 prerequisite — python3.12 not found on fresh hosts #3538 explicitly calls for an OR condition covering both ai-stack and backend, since both create Python 3.12 venvs. A standalone backend-only redeploy on a fresh host will still fail with python3.12: command not found.

AutoBot-AI/autobot-slm-backend/ansible/deploy.yml

Lines 52 to 63 in 4d16f75

	# AI/ML Roles
	# python312 must be present before ai-stack creates its venv (#3538)
	- name: Install Python 3.12 prerequisite for ai-stack
	ansible.builtin.include_role:
	name: python312
	when: "'ai-stack' in role_list"
	- name: Deploy npu-worker role
	ansible.builtin.include_role:
	name: npu-worker
	when: "'npu-worker' in role_list"

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