[FEATURE]: support JSON schema as a constrain of opencode run command

[richardanaya]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Support for new --json on opencode run command similar to llama.cpp cli

'''
opencode run -m opencode/grok-code --json '{"type":"object","properties":{"colors":{"type":"array","items":{"type":"string"}}},"required":["colors"]}' "make 3 colors"
'''

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [FEATURE]: Support for Structured Outputs in the OpenCode SDK #5639: Support for Structured Outputs in the OpenCode SDK
• Enforcing structured output (c.f. Pydantic) and offload to temporary variables? [design patterns?] #6758: Enforcing structured output (c.f. Pydantic) and offload to temporary variables
• [FEATURE]: JSON Schema as Source of Truth for API Contracts #6879: JSON Schema as Source of Truth for API Contracts
• [FEATURE]: --format json does not print reasoning_content. #7202: --format json does not print reasoning_content

Feel free to ignore if none of these address your specific case.