docs(learnings): add /eval/simulation/* API endpoint reference (#13)

Appends a full API reference section to simulations.md covering all
six controllers: simulation, scenario, personality, suite, run +
run items, and AI scenario generation. Includes request/response
shapes, query params, auth scopes, and validation rules grounded in
the DTOs at libs/core/src/types/simulation.types/.

Also fixes the stale POST /eval/simulation/suite/{suiteId}/run curl
example — it's been replaced by the unified POST /eval/simulation/run
with discriminated simulations[] entries.

Author: dhruva-vapi

docs/learnings/README.md

@@ -41,7 +41,7 @@ Gotchas and silent defaults for each resource type:
 | [assistants.md](assistants.md) | Model defaults, voice, transcriber, firstMessage, outbound modes, voicemailMessage, hooks, idle messages, endpointing, interruption, analysis, artifacts, background sound, server messages, HIPAA, tool resolution |
 | [squads.md](squads.md) | Name uniqueness, tools:append, assistantDestinations, handoff context, contextEngineeringPlan, VM detection relay pattern, override merge order |
 | [structured-outputs.md](structured-outputs.md) | Schema type gotchas, assistant_ids, default models, target modes, KPI patterns |
-| [simulations.md](simulations.md) | Personalities, evaluation comparators, chat-mode gotcha, missing references |
+| [simulations.md](simulations.md) | Personalities, evaluation comparators, chat-mode gotcha, missing references, full `/eval/simulation/*` API reference |
 | [webhooks.md](webhooks.md) | Default server messages, timeouts, unreachable servers, credential resolution, payload shape |
 
 ### Troubleshooting Runbooks