feat: igla-trainer + anti-ban audit + Dockerfile — Closes #122 #123 #124

[gHashTag]

Summary

• igla-trainer ([ALFA] igla-trainer Rust skeleton (was A1) #122): Air-gap PBT-safe trainer skeleton with audit log, LR schedules (flat/cosine/phi-warmup), config, and JSON output. Runnable: cargo run -p igla-trainer.
• anti-ban-audit ([A5] anti-ban audit harness #124): Verification tool that checks L7 (no .sh), clippy, and tests. Exits 1 on any violation.
• Dockerfile + railway.toml ([BRAVO] Dockerfile + railway.toml (was A2) #123): Multi-stage build + Railway deploy config.
• TECH_DEBT.md: Resolved TD-015, TD-017, TD-018. Only 1 active debt remaining (TD-016 Chrome TS).

Verification

cargo clippy --all-targets --all-features -- -D warnings  # 0 errors
cargo test --workspace                                    # 80 suites, 0 failed

Closes #122 #123 #124