[FEAT] Add on-chain signature verification for decrypt results

[roeezolantz]

Summary

Enables SDK/JS users to publish decryption results directly to the TaskManager contract with cryptographic signature verification from the threshold decryption network.

Main Changes

TaskManager.sol:

• Added publishDecryptResult() - publish signed decrypt result to chain
• Added publishDecryptResultBatch() - batch publish for gas efficiency
• Added verifyDecryptResult() - verify signature without publishing (view, reverts on invalid)
• Added verifyDecryptResultSafe() - verify signature without publishing (view, returns false on invalid)
• Added decryptResultSigner state variable and setDecryptResultSigner() admin function, triggering DecryptResultSignerChanged event upon change

ICofhe.sol / FHE.sol:

• Added interface definitions and wrapper functions
• Typed overloads for all encrypted types (ebool, euint8, euint16, euint32, euint64, euint128, eaddress)
• Impl layer uses bytes32 for ctHash, matching the existing pattern (e.g. getDecryptResult(bytes32))

Message Format: result (32 bytes), enc_type (4), chain_id (8), ct_hash (32) = 76 bytes total

Examples

taskManager.publishDecryptResult(0x123..., 42, 0xsig...)
FHE.publishDecryptResult(ctHash, result, signature)

taskManager.publishDecryptResultBatch([hash1, hash2], [42, 100], [sig1, sig2])

bool valid = taskManager.verifyDecryptResult(0x123..., 42, 0xsig...)
bool valid = FHE.verifyDecryptResult(ctHash, result, signature)

// Non-reverting version (returns false instead of reverting)
bool valid = taskManager.verifyDecryptResultSafe(0x123..., 42, 0xsig...)
bool valid = FHE.verifyDecryptResultSafe(ctHash, result, signature)

taskManager.setDecryptResultSigner(0xDispatcherAddress)

address signer = taskManager.decryptResultSigner()

[roeezolantz]

@liorbond didn't rebase on the CTA PR yet, but fixed everything else, please re-review :)

[roeezolantz]

@liorbond I've added some fixes :

• C-1: Use ECDSA.tryRecover instead of recover so verifyDecryptResultSafe returns false on malformed signatures instead of reverting
• H-2: Added onlyIfEnabled modifier to publishDecryptResult and publishDecryptResultBatch
• Replaced require string with LengthMismatch custom error in batch function
• Added safety comment in assembly and advance free memory pointer to be on the safe side if this function ever get changed in the future and the data is needed
• Changed Impl functions to accept bytes32 for ctHash (matching getDecryptResult pattern) - based on the CTA rebase
• Added verifyDecryptResultSafe typed overloads for all encrypted types
• Added EADDRESS_TFHE to encryption types test coverage