fix: preserve explicit chat provider parameters

[voodoohop]

• Forward explicit OpenAI-compatible top_k and Azure parallel_tool_calls, including false; omitted values stay omitted.
• Preserve Claude reasoning effort and map JSON-schema output using the current AWS Converse format. Leave json_object and Claude parallel-tool controls unchanged; no blanket passthrough.
• Verification: 14 real-transform tests and build pass. Local Gen + gateway requests reach Azure, Bedrock, Fireworks and DeepInfra. Azure false produces one tool call, including streaming; Claude obeys a 32-token limit and returns schema-constrained JSON. Invalid schemas and unsupported OVH top_k return clear 400s.
• New tests pass in CI; changed files pass formatting. CI remains red for six existing formatting failures and broken links in untouched documentation. Typecheck has the same 12 preexisting errors as main. No unrelated cleanup included.
• Companion: pollinations#14664. Addresses forwarding bugs found during [QUEST] Expose supported parameters and defaults in model listings pollinations#14599; metadata stays separate. No deployment or credential changes.