core: add engine capability flags

[heritechie]

Goal:
Allow the core editor to reason about engine feature availability
without assuming feature parity across engines.

Tasks:

• Define a capability model exposed by MapEngineAdapter
• Capabilities should include (at minimum):
  • render
  • drawPolygon
  • editPolygon
  • geolocation
• Update core logic to check capabilities before invoking features

Acceptance:

• Core editor does not call unsupported engine features
• Secondary engines can opt out of unsupported capabilities safely
• Capability flags are discoverable during editor initialization