Improve scaffolding and practice in MCP concepts side quest

[Copilot]

workshop/side-quest-17-01-mcp-concepts.md read like a reference page: it introduced MCP concepts without anchoring learners to Step 17 and offered little active practice before the checkpoint. This update adds a clearer entry point and lightweight learner actions so the page reinforces, rather than only explains, MCP usage.

• Scaffolding

  • Added a 📋 Before You Start section that explicitly ties the side quest to Step 17 and asks learners to keep their workflow YAML open.

• Active practice

  • Added a short exercise after the agentic loop section that asks learners to inspect their own tools: block and identify the configured MCP server.
  • Added a local verification command after the tools: explanation so learners can check the block directly:

  gh aw validate

• Checkpoint alignment

  • Extended the checkpoint to include locating the learner’s own tools: block and identifying the MCP server name.
  • Tightened the opening guidance and checkpoint wording so the side quest sequence and voice stay consistent with the rest of the workshop.