Trainer party size limit is now configurable

[AerunDev]

As a Pokémon Studio user building custom gameplay experiences
I want to define trainer party size limits beyond the default of 6 Pokémon
So that I can create projects with alternative gameplay rules (e.g. larger teams), without being constrained by Studio if the underlying engine supports it

This flexibility must remain controlled and explicit, to avoid inconsistencies or unintended side effects.

Acceptance Criteria

• The default maximum party size for trainers remains 6 Pokémon.
• A project-level configuration allows defining a custom maximum party size (e.g. up to a reasonable upper bound to not fall in the "trainer is a group trap").
• The trainer editor:
  • Adapts dynamically to the configured limit.
  • Prevents exceeding the configured maximum.
• Existing projects remain unaffected unless the configuration is explicitly changed.
• The UI remains simple:
  • No per-trainer overrides in the first iteration.
  • No unnecessary complexity such as conditional teams.

Identified and Relevant Use Cases

Relevant

• Creating games with larger standard party sizes (e.g. 8 creatures instead of 6).
• Designing custom battle systems or non-Pokémon-like experiences.
• Advanced projects experimenting with alternative combat formats.

Out of Scope

• Per-trainer custom limits (adds complexity with limited immediate value).
• Full decoupling from Pokémon conventions without validation against PSDK constraints.