feat: propose managed MCP router cards

[hmishra2250]

Draft proposal

• co-deliver a small, versioned Firecrawl routing block after successful MCP setup
• target 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
• keep direct setup mcp delivery explicit (--router-card) and launch delivery default-on with --no-router-card

Important status

• draft for review only
• no release-version bump
• no auto-merge
• merging requires an explicit later release decision

Validation

• formatting, typecheck, and build pass
• 24 test files / 388 tests pass
• git diff --check passes

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