feat: scaffold e2e testing harness, move devnet dump generation to a separate script

[m-kus]

Update test fixture generation with dedicated e2e package

TL;DR

Adds a new e2e package with dedicated scripts for generating test fixtures, replacing the previous approach of using SDK tests with environment variables.

What changed?

• Created a new e2e package with a dedicated script for generating test fixtures
• Updated fixture generation instructions in READMEs to use the new approach
• Added smoke tests in the e2e package to verify the indexer works correctly
• Implemented helper classes for test environment setup and indexer client management
• Removed the old environment variable-based fixture generation from the SDK

How to test?

cd e2e && npm run generate-dump

This will regenerate all fixtures for both discovery-core and discovery-service. Then run cargo test to verify the Rust tests still pass with the new fixtures.

Why make this change?

The previous approach relied on SDK tests with environment variables to generate fixtures, which was error-prone and difficult to maintain. The new dedicated e2e package provides a cleaner, more maintainable solution with explicit scripts for fixture generation. This also sets up infrastructure for proper end-to-end testing of the entire system, including the indexer.

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This change is 

[m-kus]

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Learn more

• feat(indexer): e2e discovery flow #440
• feat(indexer): preflight endpoint, sync with abstract discovery provider interface #439
• feat(indexer): outgoing state sync endpoint #438
• feat(indexer): batch state sync #435
• feat(indexer): sync outgoing state #433
• feat(indexer): discover outgoing channels #430
• feat(indexer): find last used note index #429
• feat(indexer): outgoing channel primitives #424
• feat(indexer): filter out spent notes, use secret felt #422
• feat: scaffold e2e testing harness, move devnet dump generation to a separate script #421 👈 (View in Graphite)
• feat(indexer): sync code and spec, update guidelines and todos #414
• feat(indexer): add incoming state sync endpoint #413
• feat(indexer): api error types #412
• refactor(indexer): common helpers for spawning devnet/indexer #411
• feat(indexer): incoming state sync orchestration #410
• feat(indexer): cursor pagination for discovery #408
• refactor(indexer): reorganize discovery-core, prepare for state sync #407 : 1 other dependent PR (#453 )
• feat(ci): speed up rust workflow #415
• main

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