Update Gutenberg and RTC plugin releases

[maxschmeling]

Summary

• Adds Gutenberg integration folder vip-integrations/gutenberg-0.2-20260817.
• The artifact was built directly from Gutenberg origin/trunk commit 4849c664c38421c747542015ae5fc7bd4634e06a (plugin version 23.8.0-rc.1).
• Confirms the latest VIP RTC release is v0.4.1 and is already available through vip-integrations/vip-real-time-collaboration-0.4; the VIP RTC folder/version selection is unchanged.
• Removes no stale custom Gutenberg or RTC folders.

Deployed-stage versions preserved

• develop: Gutenberg 0.2-20260810, RTC 0.4
• staging: Gutenberg 0.2-20260810, RTC 0.4
• production: Gutenberg 0.2-20260803-pr79021, RTC 0.3

The corresponding folders gutenberg-0.2-20260810, gutenberg-0.2-20260803-pr79021, vip-real-time-collaboration-0.4, and vip-real-time-collaboration-0.3 remain present.

Validation

• Full Gutenberg plugin build succeeded under Node 20.20.2.
• Gutenberg source: 4849c664c38421c747542015ae5fc7bd4634e06a from current origin/trunk.
• Gutenberg ZIP SHA-256: 5ca1ab38bdb8025f08ab0931b72b2cb5004ae6ea8b2718ddd8ad0c1e54bcbe07.
• unzip -t gutenberg.zip passed (2,189 files; 186,009,395 uncompressed bytes).
• Confirmed the extracted plugin contains gutenberg.php and build/build.php.
• cd ci && npm test passed: 13 tests.
• Confirmed all deployed-stage integration folders remain present alongside the new folder.
• git diff --check reports whitespace in upstream generated build files; the archive was imported without modifying generated output.