Plan a burn

To plan a burn:
1. Burn Plans tab → "+ New plan"
2. **Purpose** — phasing / rendezvous / TLI / deorbit / station-keeping / contingency
3. **Engine(s)** — pick from your engine registry
4. **Time of Ignition (TIG)** — UTC + MET
5. **Target Δv** — m/s
6. **Attitude** — orbital frame vector or quaternion
7. Save → plan is in the proposed state

The planner auto-calculates:
- **Expected duration** — Δv / (thrust / mass)
- **Expected propellant burn** — using engine Isp + Tsiolkovsky
- **Tank state after burn** — current minus expected burn × mixture ratio
- **Feasibility** — green if all tanks stay above reserves; red if any go negative

Approval flow:
- Engineering review → propulsion-officer approval → flight-director approval
- Each approval is logged on the burn plan record

When TIG arrives, the burn moves to Executed Burns (auto-promote from telemetry if integrated, or manually). Wally `propulsion_planBurn` lets the propulsion officer scaffold the plan from chat.