What does this PR do?

Fixes WhatsApp ID normalization for multi-device JIDs. The format is number:device@domain (e.g. 4912345678:3@s.whatsapp.net). The previous logic used str.replace(":", "@", 1) which produced number@device@domain — a malformed ID with two @ signs.

This broke bot-self detection, mention matching, and quoted-participant checks whenever the bot or a mentioned user had a device suffix in their JID.

Fix: find the colon and @ positions, then slice out the :device segment to produce number@domain. Applied to both the Python adapter and the Node.js bridge so they stay in sync.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• gateway/platforms/whatsapp.py — _normalize_whatsapp_id(): replace naive str.replace(":", "@", 1) with position-based slicing that correctly strips the device suffix
• scripts/whatsapp-bridge/bridge.js — normalizeWhatsAppId(): same fix on the JS side so bridge and adapter stay in sync
• tests/gateway/test_whatsapp_id_normalization.py — new parametrized test covering device suffixes, LID format, group IDs, clean IDs, and edge cases (12 cases)

How to Test

1. Run the new tests: pytest tests/gateway/test_whatsapp_id_normalization.py -v
2. Connect a WhatsApp account with multi-device enabled
3. Send a message to a group where the bot is present — verify the bot detects its own messages and does not reply to itself
4. Reply to a bot message in a group — verify quoted-participant matching works

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes
• I've tested on my platform: Pop!_OS (Ubuntu-based) Linux

Documentation & Housekeeping

• I've updated relevant documentation — N/A (bug fix, no new config)
• I've considered cross-platform impact — N/A (string operations only)