Update Gutenberg and RTC plugin releases

[maxschmeling]

Summary

• Adds custom Gutenberg integration folder vip-integrations/gutenberg-0.2-20260727-pr79021.
• The artifact is built from Gutenberg trunk at 16bdc35180aafe200282699dd9eeec04d430bcde (plugin version 23.6.0) with the current consolidated changes from RTC: Fix inner template multiple insertion WordPress/gutenberg#79021 applied on top because that PR remains open.
• Confirms the latest VIP RTC release v0.3.2 remains available through vip-integrations/vip-real-time-collaboration-0.3.
• No stale custom Gutenberg folders were removed: gutenberg-0.2-20260706-pr79021 and gutenberg-0.2-20260720-pr79021 are both still referenced by deployed stages.

Deployed-stage versions preserved

• develop: Gutenberg 0.2-20260720-pr79021, RTC 0.3
• staging: Gutenberg 0.2-20260720-pr79021, RTC 0.3
• production: Gutenberg 0.2-20260706-pr79021, RTC 0.3

Validation

• Full Gutenberg plugin build succeeded under Node 20.
• Gutenberg source: trunk commit 16bdc35180aafe200282699dd9eeec04d430bcde plus the current consolidated RTC: Fix inner template multiple insertion WordPress/gutenberg#79021 diff (head 9d1b414589158addeec41d48966d571a1619eecc).
• Custom Gutenberg ZIP SHA-256: 74c864d59679adb4acffc4ee9e3fbb5a0afc19be282803ecb48939568315c880.
• unzip -tq gutenberg.zip passed.
• cd ci && npm test passed: 13 tests.
• git diff --check passed.
• Confirmed all deployed-stage integration folders remain present alongside the new folder.