add operating-point simulation result schema

[ShiboSoftwareDev]

What changed

• add typed voltage and current results for DC operating-point experiments
• add classified simulation experiment errors for non-convergence, timeouts, missing models, unsupported analyses, invalid netlists, and engine failures
• add a wall-clock timeout field to simulation experiment configuration
• include the new elements in any_circuit_element and generated documentation

Why

tscircuit already names spice_dc_operating_point as an experiment type, but Circuit JSON had no result representation for the single-point values and no structured way to distinguish convergence failures from generic engine errors.

Validation

• bun test (261 passed)
• bun run build
• bun run lint:zod
• bun run check-snake-case

Stack and merge order

1. Schema/result contract (this PR): add operating-point simulation result schema #646
2. Public props: Add operating-point simulation props props#730
3. .op netlist generation: Generate DC operating-point SPICE analyses circuit-json-to-spice#50
4. ngspice execution/result conversion: Return scalar ngspice operating points ngspice-spice-engine#25
5. SVG results and diagnostics: feat: render DC operating-point simulation results circuit-to-svg#622
6. Core integration: feat: add DC operating-point simulations core#2682