Add Agent API support to Perplexity MCP tools

[gleb-reshetnev]

Motivation

The official MCP server currently routes Claude Code, Cursor, Antigravity, and other MCP clients through legacy Sonar Chat Completions with hardcoded models. This moves the three generative tools onto the Agent API so those clients can use Agent presets and provider/model selection through the integration we own.

Linear: API-3381

What changed

• route perplexity_ask, perplexity_research, and perplexity_reason through streaming POST /v1/agent requests
• add Zod schemas for Agent requests, Responses output items, and SSE events
• assemble streamed output text and citations from all search_results batches
• expose optional model and preset tool parameters, with fast, medium, and low defaults by tool
• translate existing search filters and reasoning effort to Agent API request shapes
• keep perplexity_search on the Search API
• bump package and registry metadata to 0.10.0

Rollout

Merging the version bump publishes 0.10.0 through the repository release workflow. The public API docs update is intentionally separate and should land after that package is available.