refactor(cli): extract Petdex mascot cluster into CLIPetMixin (cli.py god-file slice R2)

[andrexibiza]

Summary

cli.py god-file slice R2: extract the Petdex mascot cluster from cli.py (18,485 lines) into hermes_cli/cli_pet_mixin.py (class CLIPetMixin). Part of the repo-wide large-file decomposition (tracker #78647).

What changed and why

• Petdex cluster (window 5613–5829, 217 lines, 13 members: _PET_FRAME_INTERVAL, _PET_CFG_INTERVAL + 11 methods) moved 218/218 bytes byte-exact into hermes_cli/cli_pet_mixin.py
• HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin, CLIPetMixin) — mixin appended last; zero __init__ change, zero caller edits; all 7 out-of-cluster call sites resolve through the MRO
• No-back-import rule: module imports only __future__/threading/time; agent.pet.* + hermes_cli.config stay lazy in-method (as in the original)
• Double-blind: 2 independent analysts → consensus (R2-CONSENSUS.md, golden sha verified) → implementer → 2 blind re-reviewers (pass A: APPROVED, 0C/0I; pass B adversarial: APPROVED, 0C/0I)

Testing

• test_cli_pet_mixin_seam.py: 13 identity asserts (getattr(HermesCLI, n) is CLIPetMixin.n), MRO-order/no-shadowing assert, no-back-import subprocess test (sys.modules['cli']=None), import-order permutation, patch-binding-through-seam, anim-loop idempotency, _on_reaction flash
• Regression battery (test_cli_pet_pane.py + test_cli_status_bar.py + test_cli_init.py + test_cli_active_agent_ref_wiring.py): 50 passed
• ruff clean · git diff --check clean · LF-only · DCO signed · Windows-tested

Coordination / interlock

• Epic: Part of [COMPLETE] Large-file decomposition: 20/20 done #78647 · Target: Part of Refactor cli.py God-File (UI & Commands Extraction) #55136
• Sibling PRs: the 3 other cli.py wave-1 slices (tui-hooks, modal-confirm, usage) — disjoint windows, same wave
• R1 coordination: refactor: extract cli_config, cli_git, cli_display from cli.py (−2,158 lines) #12355 (open, 2,158-line cli extraction) overlaps cli.py's R1 region only — R2 is outside its windows; coordination comment posted there
• Dedup: no existing PR extracts the Petdex cluster (verified via 60-PR open-PR sweep)

Part of #78647
Part of #55136

[andrexibiza]

🔒 This shard is part of the cli.py KILL LOCK — the permanent record of the 18,485-line whole, the mess it caused (#54960 duplicate-tracking chaos, #65303 no ESC-interrupt, #72797 XML-tag loss, #75461 redaction bypass, #76914 unfinalized sessions, #77764 approval truncation, #39446 /reload-mcp blocking, terminal-escape leaks), every shard in the wave, the #12355 block on R1, and every open fixer PR still fighting the surface (#73104 #75476 #77776 #75084 #76804 #76995 #71295 #78871 #74491 #72821 #57453 #61429 #71027 #62027 #65192 #71088 #74038 #69918 #67484 #12355 #75207 #32193 #74281 #37818 #27172 #65785).

Lock: posted on #55136 · Indexed by the Kill All Gods meta-issue #78647.