Fix GaugeGap production deploy gate

[slavazeph-coder]

Fix

The GaugeGap homepage was merged successfully, but the Railway workflow still grepped for the previous BrainSNN title during both local boot validation and the post-deploy healthcheck. That made the new build fail its own deployment gate.

This PR:

• updates both deploy markers to GaugeGap Foundry | Play with the impossible
• updates the PWA manifest to GaugeGap Foundry
• replaces the old SNN favicon with the GaugeGap G mark

Merging this PR retriggers the existing push-to-main Railway deployment workflow.

[gemini-code-assist]

Code Review

This pull request updates the branding assets and metadata for the application. Specifically, it modifies the SVG favicon by updating its gradient colors, adjusting border radii, and replacing the 'SNN' text with a custom path. Additionally, the web manifest is updated to reflect the new name 'GaugeGap Foundry by BrainSNN', along with an updated description and theme colors. I have no feedback to provide.

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