fix(vscode-extension): skip inaccessible filesystem entries during activation scan

[qfai]

Summary

This change prevents extension activation from failing when workspace scanning encounters inaccessible filesystem entries.

Repro (Windows PowerShell)

mkdir .repro-denied
echo "x" > .repro-denied\dummy.txt
icacls .repro-denied /inheritance:r
icacls .repro-denied /deny "(OI)(CI)RX"
code .

Then run Developer: Reload Window and check Log (Extension Host).

Expected

Extension activates successfully and skips unreadable entries.

Actual (before fix)

A single EACCES/EPERM during recursive traversal can abort activation.

Fix

Add per-entry guards in recursive scanning logic:

• protect directory listing
• protect metadata checks
• protect optional JSON reads
• continue traversal on access errors

Validation

• Reproduced activation failure with an unreadable directory (before fix).
• Verified activation continues after this change by skipping inaccessible entries.