fix(amazon-bedrock): correct Gemma catalog

[rekram1-node]

Summary

Google/Gemma-only split of #6794, based on current dev.

• Add complete provider-agnostic Gemma 3 lab metadata.
• Convert Bedrock Gemma 3 entries to override-only base_model files with corrected prices and host limits.
• Keep lab tool_call = true, but override Bedrock to false: forced tool calls work, while valid native tool-result continuation fails on all three sizes.
• Add three live-verified Gemma 4 Mantle Responses entries with none/high reasoning effort and structured JSON support.

Sources and live-check notes are in leading TOML comments.

Validation

• bun validate
• New labs include all required capabilities, modalities, context and output
• git diff --check
• No removals or route changes

[github-actions]

No actionable findings.