Add skill: puzzle-activity-planner

[fruitwyatt]

Adds a puzzle activity planner skill that helps plan multi-puzzle sessions for classrooms, parties, team-building, and events.

What it does:

• Generates structured activity plans with timing, materials, and differentiation tips
• Outputs pre-configured generator links with URL parameters pre-filled (words, clues, grid size, etc.)
• Covers 5 puzzle types: word search, crossword, sudoku, bingo, and jigsaw

Skill repo: https://github.com/fruitwyatt/puzzle-activity-planner