⚡ Optimize dependency checking in shadcn-ui verify script

[davideast]

💡 What: Optimized the dependency checking loop in skills/shadcn-ui/scripts/verify-setup.sh by reading package.json once into a variable and using Bash-native string matching instead of calling grep repeatedly.
🎯 Why: Calling grep in a loop spawns a new process for each dependency, which is inefficient. Using Bash built-ins significantly reduces I/O and process overhead.
📊 Measured Improvement: In a benchmark with a 1000-line package.json and 100 iterations (each checking 6 dependencies), the execution time was reduced from ~1.57s to ~0.62s, representing a ~60% speed improvement for that section of the script.

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PR created automatically by Jules for task 13154819874040057461 started by @davideast

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