fix(ci): atomic fix for #46 deadlock — rename job + cargo fmt

[gHashTag]

🎯 Goal

Resolve the CI naming deadlock in one atomic commit.

🐛 Deadlock situation

PR #43 (fmt)   → BLOCKED  → waits for "ci" check (doesn't exist)
PR #47 (rename)→ FAILING  → cargo fmt check finds unformatted code

Both PRs need each other to proceed — circular dependency.

✅ Atomic fix

This PR combines both changes in one commit:

1. Rename job build-and-test → ci in .github/workflows/ci.yml
2. Apply cargo fmt to satisfy the 'ci' job's formatting check

Result: CI job runs with name "ci" (matches branch protection) + code is formatted → CLEAN

📋 Files changed

• .github/workflows/ci.yml — job rename + docker needs update
• src/bin/cpu_train.rs — fmt
• src/model_hybrid_attn.rs — fmt
• src/train_loop.rs — fmt

✅ Acceptance

• Job name matches required_status_checks.contexts = ["ci"]
• cargo fmt passes on all files
• CI runs green → PR becomes CLEAN
• Downstream PRs (fix(promotion-E): cargo fmt + resolve duplicate HybridAttn::backward post un-revert b10c8e0 #43, feat(promotion-D): publish trainer image as ghcr.io/ghashtag/trios-train:latest #42, fix(gate-final): remove seed 45 from seed_results.jsonl #44, chore(L1): purge all .sh — Rust-only replacements (entrypoint, deploy helpers) #45) unblock on merge

Closes #46
Related to #43

φ² + φ⁻² = 3 · TRINITY · NEVER STOP