fix(app): handle empty Android Firebase JSON

[OskarEichler]

Compatibility

• No public API or type changes.
• No breaking changes.
• Observable correction: jsonGetAll now returns an empty map when no firebase.json React Native settings exist instead of crashing on Android.

What changed

• Iterate JSONObject keys directly, which handles an empty object and avoids allocating a JSONArray of key names.
• Return the already-created empty bridge map if parsing was unavailable.
• Add a focused Robolectric regression for the default empty-object configuration.

Verification

• Exact regression fails on upstream main with NullPointerException and passes with this change.
• Full App Android unit suite passes.
• App Android debug AAR assembly and lint pass.
• Repository Android formatting and whitespace checks pass.

[mikehardy]

this looks good but needs to drop the robolectric pin using some work I've got in-flight elsewhere - queueing this for a quick edit after that lands, to rebase the other work in and remove the pin

[mikehardy]

I've got a PR in flight that drops this - the sdk = 34 robolectric pin is idiomatic in the codebase but is unnecessary and will result in unnecessary robolectric implementation jars in the future