v1.5.5+319: bump after Apple closed v1.5.4 train

Apple's App Store Connect closed the v1.5.4 train for new build
submissions after approving v1.5.4+318 earlier today, returning
errors 90186 (Pre-Release Train closed) and 90062 (CFBundleShort
VersionString must be higher than the previously approved version).
Bumping marketing version 1.5.4 → 1.5.5 to ship the audit fixes
+ 6 rounds of Codex 5.5 review fixes that landed in 946c308..401dbec.

Build pipeline used:
- export LANG=en_US.UTF-8 (CocoaPods 1.16.2 + Ruby 4.0 normalization
  bug on paths with spaces)
- flutter clean / pub get / build_runner / build appbundle / build ipa
- IPA uploaded via altool API key 77HSQA4SZD (no Xcode Organizer
  needed; the prior 'altool 401s' memory was wrong)
- AAB ready for Play Console upload

Author: RedGridTactical

pubspec.yaml

@@ -1,7 +1,7 @@
 name: red_grid_link
 description: Offline-first MGRS-native proximity coordination platform
 publish_to: 'none'
-version: 1.5.4+319
+version: 1.5.5+319
 
 environment:
   sdk: '>=3.2.0 <4.0.0'