fix: E2EE message content extraction for URLs and link attachments

[Copilot]

E2EE messages containing URLs were returning empty content, and link attachment metadata was not being extracted from encrypted messages.

Changes

• E2EE text extraction: Added fallback chain for ExtendedTextMessage (text → matchedText → canonicalURL) to ensure URL-containing messages have content
• Armadillo message parsing: Added support for ExtendedContentMessage to extract link shares and extended content from special message types
• Link attachment metadata: Extract title, description, and source domain from both ConsumerApplication and Armadillo message types
• URL redirect handling: Parse actual URLs from Facebook's /l.php redirect links

Type definitions

Added fields to Attachment interface for link metadata:

interface Attachment {
  // For link attachments
  description?: string    // Link description/subtitle
  sourceText?: string     // Source domain text
}

Implementation details

• extractE2EEText(): Extended to handle Armadillo messages with CTAs and canonical URLs
• extractE2EEMessage(): Enhanced ExtendedTextMessage parsing to preserve text while creating link attachments
• extractArmadilloLinkAttachment(): New helper to extract link metadata from Armadillo XMA messages

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