Add automatic execution routing

[EricSun0218]

What changed

• make bounded hybrid automatic routing the default for durable Direct, Agent, and Workflow execution
• keep obvious dialogue on the one-turn Direct path while preserving Agent capabilities for actionable, structured, long, or ambiguous input
• add optional ambiguity classification and route-selected inference/provider profiles without overriding per-run controls
• preserve declared capability requirements, conservative timeout fallback, and the existing four-argument public decision constructor
• document the shared behavior for the core runtime, Godot, and Unity

Developer impact

Games can pass arbitrary bounded structured signals or normal transcript input and receive automatic path selection without paying for an extra classifier call on obvious requests. Applications may opt into a classifier only for ambiguous text and may configure distinct model profiles for Direct and Agent work.

Validation

• Release build: 0 warnings, 0 errors
• Full solution tests: 1,906 passed
• Routing tests: 37 passed
• Unity host tests: 85 passed
• Godot editor/plugin tests and samples passed
• Unity UPM package, clean-consumer compilation, privacy, assembly-load, and self-test gates passed
• Godot and Unity clean-room integration benchmark passed
• tracked-source privacy, trusted workflow, version consistency, formatting, and public-reference scans passed