Fix OpenCode provider yielding zero usage (#392)

[iamtoruk]

Summary

• Broaden part type recognition: tool-call, tool_call, tool-result, tool_result, reasoning, file now count as activity (previously only text and tool)
• Accept role: "model" as equivalent to role: "assistant"
• Fall back to data.usage.{input_tokens, output_tokens, ...} when data.tokens is absent
• Fall back to data.model when data.modelID is absent
• Add session-level token fallback: when per-message parsing yields zero calls, read aggregated tokens from session row columns (tokens_input, tokens_output, etc.)
• Add --verbose diagnostic showing parse/skip counts when zero calls are yielded

Test plan

• All 43 OpenCode provider tests pass (4 new tests added)
• Full suite passes (979 tests)
• Reporter confirms fix resolves their zero-usage issue

Closes #392