Update default Electrum Server config to use Electrs instead of Fulcrum

[ovitrif]

TODO once the new backend server is fully synced.
Must do (at least) one full testing session on both platforms afterwards before submitting the 1st RC build.

[ovitrif]

@claude implement this based on the Android counterpart in:

synonymdev/bitkit-android#694

Focus first on the electrum server defaults change and make sure it's committed separately from the other changes, in case we conclude the others are not needed on iOS we should be able to just HARD reset branch to the relevant commit.

[claude]

Claude finished @ovitrif's task in 1m 45s —— View job • claude/issue-367-20260122-1118 • Create PR ➔

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Task Complete

Summary

Updated the default Electrum server configuration from Fulcrum to Electrs for Bitcoin mainnet.

Changes Made

Commit: feat: update default Electrum server from Fulcrum to Electrs (40659a7)

• Updated mainnet Electrum server URL in Bitkit/Constants/Env.swift:123
• Changed from: ssl://fulcrum.bitkit.blocktank.to:8900
• Changed to: ssl://electrs.bitkit.blocktank.to:8900

Notes

• The change has been committed separately as requested, making it easy to reset to this commit if other changes are determined to be unnecessary
• Regtest environment still uses Fulcrum (staging): ssl://fulcrum.bitkit.stag0.blocktank.to:18484
• All other Electrum-related code dynamically uses the configuration from Env.swift, so no additional code changes were needed
• E2E tests use local Electrum backend and are not affected by this change

Testing Required

As mentioned in the issue, at least one full testing session should be performed on both platforms before submitting the first RC build.

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[jvsena42]

Test case:

1. Migratre from RN
2. Go to electrum server options
3. Reset do default
4. Should default to the new address
5. Connect

[jvsena42]

@ovitrif isn't the mainnet address ssl://bitkit.to:9999 ?

[ovitrif]

@ovitrif isn't the mainnet address ssl://bitkit.to:9999 ?

Indeed, dadgummit, Claude 🤦🏻