feat(ai): supercharge ARIA system prompt with per-platform mastery playbooks

- Replace short one-line device descriptions with deep playbooks per platform
  (signature commands, common root causes, diagnostic flow) for: Cisco IOS / IOS-XE / NX-OS / ASA, Junos, Arista EOS, FortiOS, PAN-OS, MikroTik, HP/Aruba, Nokia SR-OS, Huawei VRP, F5 TMOS, Linux, Windows
- Expand certifications to principal-grade multi-vendor expert (CCIE x4, JNCIE x4, NSE 8, CWNE, VCDX, CKS, AWS/Azure/GCP networking)
- Add RFC-level protocol depth section (BGP extensions, MPLS/SR/SRv6, EVPN, IKEv2, QUIC, etc.)
- Stronger engineering personality (calm, surgical, evidence-driven)
- Stricter operational rules: evidence-driven diagnosis, explicit response format (Finding/Root cause/Impact/Fix/Verify/Rollback), command economy, pager handling, security posture
- Mode descriptions are now exhaustive (allowed verbs in troubleshoot, mandatory pre-change checklist in full-access)

Author: AnasProgrammer2