Shadow Harvester 0.2.0

This release marks a fundamental architectural shift, moving the miner from a fragile,
synchronous model to a robust, multi-threaded, reactive system. The core focus was
decoupling hashing from network latency, improving crash resilience,
and transitioning to a modern database for state management.

⚠️ IMPORTANT: STATE MIGRATION REQUIRED

Since this release moves from file-based state (receipts, indices) to an embedded
Sled database, all users must run the migration tool once to preserve their
history and resume mnemonic mining correctly.

shadow-harvester migrate-state --old-data-dir ./ --data-dir <your_sled_path>

• Failure to run this command will result in the miner starting over at index 0
  and ignoring any previously completed challenge progress.

🚀 Major Architectural Overhaul

• Reactive, Multi-Threaded Core: The application logic is refactored into a reactive, channel-based (mPSC) architecture. This cleanly separates responsibilities among dedicated worker threads: Challenge Manager, State Worker, and Network Polling.
• Sled Database Integration: All critical state data (receipts, challenge data, and mnemonic progress) has been migrated from the legacy file-based system to a fast, crash-safe, embedded database (Sled).
• Asynchronous Submission Queue: Hashing is decoupled from network I/O. Solutions are now written to a local disk queue, and a dedicated State Worker thread handles submission retries in the background, preventing API instability from stopping the mining process.

🛡️ Resilience and State Management

• Crash Recovery Implemented: Solutions found by the miner are saved using an atomic, two-stage persistence process (local file -> Sled queue). This ensures no valid nonce is lost if the miner crashes or loses power.
• Robust Mnemonic Resumption: The logic for Mnemonic Sequential Mining now correctly recovers the last processed index by reading addresses and derivation paths from the Sled database, guaranteeing continuity.
• Server Stability: The submitter thread now correctly identifies and retries transient 5xx Internal Server Errors instead of treating them as fatal validation failures.
• Donation Tracking Removed: All logic for submitting and tracking donation transactions was removed, simplifying the core architecture.

💻 New CLI Commands and Debugging Tools

All commands requiring state access are now nested under challenge or wallet, providing precise inspection capabilities.

Challenge State Commands (shadow-harvester challenge)

Command	Functionality
challenge list	Lists all unique Challenge IDs stored in the local database.
challenge info --id <ID>	Dumps the full JSON details for a specific challenge configuration.
challenge details --id <ID>	Outputs structured mining details (ROM Key, Difficulty) along with aggregated local counts of completed solutions and pending submissions.
challenge import --file <path>	Imports a custom challenge JSON file into the Sled database for testing or custom mining.
challenge receipt-info	Dumps the full JSON receipt stored for a specific challenge_id and address.
challenge pending-info	Dumps the full JSON for a specific pending solution waiting in the submission queue.

Wallet State Commands (shadow-harvester wallet)

Command	Functionality
wallet list	Lists unique wallet identifiers (<Mnemonic Hash>:<Account Index>) found in the database.
wallet addresses --wallet <hash:account>	Lists all known Cardano addresses and their derivation indexes associated with that wallet identifier.
wallet list-challenges --address <addr>	Lists all Challenge IDs for which the specified address has a successfully completed receipt.