Add Godot WebBridge for Stellar and ZK callbacks

[Vinaystwt]

Dependency note

This PR is stacked on top of #49 / issue #33 and #51 / issue #48 because the WebBridge depends on the base Godot project and Web export flow.

Submitting now so #36 can be reviewed in parallel. Once #49 and #51 are merged, I’ll rebase this branch onto latest main so the final diff contains only the #36 WebBridge changes.

Summary

• Add Godot WebBridge autoload for browser-side Stellar/ZK calls
• Add browser adapter at godot/web/stellar_bridge.js
• Register async callbacks from JavaScript back into Godot signals
• Add Web export head include for the bridge script
• Copy the bridge script beside dist/index.html during export
• Document the browser/Godot bridge contract
• Add Node tests for the browser adapter

What changed

• Added godot/autoloads/WebBridge.gd
• Added godot/web/stellar_bridge.js
• Added godot/web/stellar_bridge.test.js
• Added godot/web/README.md
• Registered WebBridge in godot/project.godot
• Updated godot/export_presets.cfg to include stellar_bridge.js
• Updated make godot-export to copy the bridge file into dist/
• Updated README with WebBridge documentation link

Verification

• node --test godot/web/stellar_bridge.test.js passed
• node --check godot/web/stellar_bridge.js passed
• make -n godot-export passed
• git diff --check passed
• Confirmed no dist/, .godot/, .import, or .uid artifacts are included

Note: Godot runtime/export verification was not run locally because godot4/godot is not installed in PATH.

[leocagli]

Hi @Vinaystwt — this conflicts with main. Could you rebase and resolve? Ready to merge once clean. 🙏

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud