#15786: fix: strip device suffix from selfJid in WhatsApp mention matching

## Problem When WhatsApp runs as a linked device, the `selfJid` has a device suffix (e.g., `6580835862:2@s.whatsapp.net`). The regex intended to strip this suffix used `/:\\d+/` (escaped backslash + literal 'd') instead of `/:\d+/` (colon + digits), so the suffix was never removed. This caused `wasMentioned` to always be `false` in group chats because the `normalizedMentionedJids` (E.164 format like `+6580835862`) could never match the unstripped `selfJid`. ## Fix Changed the regex from `/:\\d+/` to `/:\d+/` in three places: - `src/web/auto-reply/mentions.ts` — `resolveMentionTargets` - `src/web/auto-reply/monitor/group-gating.ts` — `applyGroupGating` (selfJid + replySenderJid) Fixes #15783 <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR fixes WhatsApp mention matching on linked devices by correcting the regex used to strip the `:<device>` suffix from JIDs. Specifically, it updates `/:\\d+/` (which matches a literal `\d`) to `/:\d+/` in `resolveMentionTargets` and in group gating’s implicit-mention comparison, so `selfJid` / `replyToSenderJid` normalize from e.g. `6580…:2@s.whatsapp.net` to `6580…@s.whatsapp.net` and can match expected mention targets. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Changes are small, localized, and correct a plainly broken regex that previously could not match WhatsApp linked-device JID suffixes. The updated regex aligns with existing JID parsing elsewhere in the repo and does not alter control flow beyond intended normalization. - No files require special attention _{Last reviewed commit: b80085d} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->