Wire job CLI subcommands into main.rs

[jeremymanning]

Parent: #7

Wire job submission CLI (submit, status, results, cancel, list) from src/cli/submitter.rs into main.rs. Subcommand struct exists.

Files: src/main.rs, src/cli/submitter.rs

[jeremymanning]

Resolved by PR #58 (spec 003-stub-replacement). All 77 tasks complete, 489+ tests passing, CI green on Linux/macOS/Windows.