Feat/multi 284 286 289 283

[sweetsoul21]

This PR implements issues #284, #286, #289, and #283 on a unified feature branch:

• Atomic Initialisation (Initialise both contracts atomically with deployment #284): Contracts are atomically initialized via native Soroban __constructor at deployment time. init is guarded with admin auth and reject subsequent calls with AlreadyInitialized. Deploy scripts updated to pass -- --admin and error trap updated.
• rescue_stream Tests (Add tests for rescue_stream #286): Full coverage of rescue_stream in donation-vault asserting exact balance transfers, resulting state, NotPaused, StreamCancelled, StreamNotFound, event topics/data, and admin authorization.
• AdminRenounced Errors (Add tests for AdminRenounced behaviour #289): Explicit coverage asserting Error::AdminRenounced for admin(), init (post-renounce), propose_admin, pause, and admin-gated calls.
• Paginated NGO Listing (Add a way to list registered NGO owners #283): Added list_ngos(start, limit) with bounded persistent storage per-entry indexing, swap-and-pop removal, TTL extension, and cap of 50.

Closes #284
Closes #286
Closes #289
Closes #283

[drips-wave]

@sweetsoul21 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits