feat: Add getCurrentUser API Method to Formulus

[najuna-brian]

PR Description

Overview

Adds a new getCurrentUser() method to the Formulus API that retrieves the authenticated username from the device's secure Keychain storage. This enables WebView apps (like AnthroCollect) to access the logged-in user information without requiring manual re-selection.
Closes https://github.com/Omo-Valley-Research-Project/AnthroCollect/issues/32

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Changes

File	Change	Description
FormulusInterfaceDefinition.ts	✅ Add getCurrentUser()	API interface definition
FormulusMessageHandlers.types.ts	✅ Add onGetCurrentUser	Message handler type
FormulusMessageHandlers.ts	✅ Implement handler	Fetch username from Keychain
generateInjectionScript.ts	🐛 Fix TypeScript syntax bug	Remove invalid interface in .js output
FormulusInjectionScript.js	✅ Regenerated	Includes new method
formulus-api.js	✅ Regenerated	JSDoc updated

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Implementation

API Method Signature:

getCurrentUser(): Promise<{username: string, displayName?: string}>
Return Value Example:

{
  username: "Eshetu",
  displayName: "Eshetu"
}

How It Works:

1. WebView (AnthroCollect) calls window.formulus.getCurrentUser()
2. Formulus Bridge invokes onGetCurrentUser handler
3. React Native Keychain returns stored credentials
4. WebView receives {username: "Eshetu", displayName: "Eshetu"}

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Bug Fix Included

Issue: Injection script generator was outputting invalid TypeScript syntax in JavaScript files

This was causing linter errors like "Expression expected" and "Declaration or statement expected"

Fixed by removing TypeScript interface declarations from the JavaScript output template

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Dependencies

Required by the corresponding AnthroCollect PR that removes the redundant user selection screen

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Testing Checklist

• Build and install Formulus Android app with these changes
• Login with fieldworker credentials (e.g., "Eshetu")
• Load AnthroCollect WebView
• Verify getCurrentUser() returns correct username
• Verify injection script has no syntax errors
• Test on both Android and iOS (if applicable)

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Technical Notes

• Username is stored in Keychain during login (Keychain.setGenericPassword)
• Method uses Keychain.getGenericPassword() to retrieve credentials securely
• Returns displayName field for future extensibility (e.g., mapping to full names)
• No breaking changes to existing API methods
• Injection scripts are auto-generated - run npm run generate after modifying the interface

Screenshot showing username an village

[najuna-brian]

This is required for https://github.com/Omo-Valley-Research-Project/AnthroCollect/pull/36 to be merged

[Mishael-2584]

I really like the current user addition to app. And overall a smarter way to avoid selection and remove the user selection screen.