fix: dirs hot reload without wildcards

[ilyaliao]

Description

This PR fixes hot reload functionality when dirs is configured without wildcards.

Previously, hot reload only worked for patterns like ./composables/* or ./composables/** but failed for ./composables:

// ✅ Works (with wildcards)
dirs: ['./composables/*', './composables/**']

// ❌ Broken (without wildcards) 
dirs: ['./composables']

The issue was that picomatch couldn't properly match files against directory paths without glob patterns.

The fix normalizes directory paths using unimport's normalizeScanDirs to properly handle both wildcard and non-wildcard patterns, ensuring files are correctly matched regardless of configuration style.

As an additional optimization, it now skips hot reload checks for auto-generated config files to prevent unnecessary re-scans.

Linked Issues

resolved #583

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