feat: deliver managed MCP router cards

[hmishra2250]

Summary

• co-deliver a small, versioned Firecrawl routing block with successful MCP setup
• use harness-native project instruction files for Claude, Codex, OpenCode, Hermes, OpenClaw, Cursor, and VS Code
• preserve unrelated project guidance with atomic, idempotent, symlink-safe writes
• make direct setup mcp delivery explicit (--router-card) and launch delivery default-on with --no-router-card
• release as CLI 1.19.25

Validation

• formatting, typecheck, and build pass
• 24 test files / 388 tests pass
• npm package dry-run includes router JS, declarations, and docs
• CLI option help smoke passes

Experiment trace data remains in Convex; no raw experiment results are committed here.