handle case-insensitive vCard tags and UID property

[mateeaaa]

Summary

This PR resolves an issue in ImportController where vCard files containing lowercase or mixed-case property tags (such as begin:vcard, end:vcard, or uid:...) were either skipped entirely or had their UID ignored during import.

Context & Root Cause

According to RFC 6350 Section 3.3 and RFC 2426, vCard property and parameter names are case-insensitive. Some contact export utilities output vCard delimiters and properties with lowercase or mixed-case formatting.

In ImportController.php:

1. The parser checked $line === 'BEGIN:VCARD' and $line === 'END:VCARD' with strict case comparison. If a .vcf file contained begin:vcard, $currentContact was never initialized, causing contacts to be silently skipped.
2. The check str_starts_with($line, self::UID_PREFIX) checked strictly for uppercase UID:. When a contact had uid:..., $currentContactUid remained null, preventing the existing contact deduplication lookup ($addressBook->search($uid, ...)) from executing and leading to duplicate entries upon re-import.

Solution

• Use strtoupper($line) when comparing against BEGIN:VCARD and END:VCARD.
• Use str_starts_with(strtoupper($line), self::UID_PREFIX) to reliably extract the UID regardless of casing.

Changes Made

• lib/Controller/ImportController.php: updated BEGIN:VCARD, END:VCARD, and UID: tag checks to be case-insensitive.

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