Upgrade to Sigma 6.0 (EIP-50) with Prover-Evaluated Tests (Closes #250)

[a-shannon]

Fixes #250.

Summary

Upgrades Appkit to sigma-state 6.0.2 and ergo-wallet 6.0.0 so Appkit can compile and prove Sigma 6 / EIP-50 scripts while preserving legacy v5 script behavior.

Supersedes #251.

Main Changes

• Replaces Sigma 5 package usages with the Sigma 6 AST, data, and serialization APIs.
• Adds blockVersion-aware ErgoScript compilation. Contexts with blockVersion >= 4 compile v6 scripts as ErgoTree v3 via VersionContext; older contexts keep the legacy path.
• Replaces removed or fragile Iso collection conversions with explicit Scala/Java conversion helpers.
• Adds prover-evaluated Sigma 6 feature coverage using v6 node mock parameters and input-box guard scripts.

Test Coverage

• Sigma 6 feature tests cover bitwise and shift ops, serialize, deserializeTo, fromBigEndianBytes, startsWith, lazy getOrElse paths, Box.getReg, Header.checkPow, UnsignedBigInt / toUnsignedMod, and v5/v6 tree-version behavior.
• Conversion coverage covers SigmaProp / ErgoTree bytes, ContextVar / ContextExtension including duplicate-id rejection, spending-proof context vars, token/register conversions through box and transaction paths, and ScalaBridge transaction conversions.
• Focused local checks passed for the common, libImpl, and appkit suites listed in the latest PR comment.

[a-shannon]

Thanks, all requested changes should now be addressed:

• removed refactor_imports.py
• removed the README Sigma 6.0 section
• reverted the unchanged PPTX
• standardized Java/Scala conversion style
• replaced the map entry loop with forEach
• combined the ScalaBridge sigma.ast imports

I also re-ran the local checks and publication guard. Could you re-review when you have a chance?

[a-shannon]

Thanks. I pushed a focused conversion coverage pass in 482f1e1.

Added/confirmed tests for each explicit runtime conversion family touched by #253:

• SigmaProp/ErgoTree byte conversion, including invalid input rejection
• ContextVar <-> ContextExtension conversion, including duplicate id failure
• SpendingProof/SignedInput context variable conversion with real signed inputs
• Token id/value conversions through box candidate, input, output, and signed transaction paths
• Scala/Java bridge conversions for spending proofs, context extension values, transaction inputs/data inputs/outputs, tokens, and registers
• v6 blockVersion/treeVersion activation and prover-evaluated Sigma 6.0 scripts via the existing Sigma60FeaturesSpec
• token burn conversion via the existing reducer negative tests

Checks run:

• sbt ++2.13.16 "common/testOnly org.ergoplatform.appkit.ErgoValueSpec org.ergoplatform.appkit.ErgoTreeTemplateSpec org.ergoplatform.appkit.ReducedErgoLikeTransactionSpec" "libImpl/testOnly org.ergoplatform.appkit.impl.ScalaBridgeTest" "appkit/testOnly org.ergoplatform.appkit.AddressSpec org.ergoplatform.appkit.TxBuilderSpec org.ergoplatform.appkit.ErgoAuthSpec org.ergoplatform.appkit.JavaHelpersSpec org.ergoplatform.appkit.ApiClientSpec org.ergoplatform.appkit.Sigma60FeaturesSpec org.ergoplatform.appkit.ChangeOutputSpec org.ergoplatform.appkit.AppkitProvingInterpreterSpec org.ergoplatform.appkit.MultiProveDlogSpec org.ergoplatform.appkit.MultiProveDHTSpec org.ergoplatform.appkit.DHTProverSpec" - pass
• publication guard on staged diff and pushed range - pass

I also tried full sbt ++2.13.16 test; the focused Appkit/common/libImpl suites above pass, but the full aggregate run still includes existing generated/live-node UtxoApiTest failures and existing SecretStorageSpec file-state failures on this environment.

[a-shannon]

@satsen pushed one final cleanup in 680f29c: Address.getPublicKey() now keeps the precise ProveDlog type exposed by Sigma 6, removing the remaining cast.

I also resolved the six May 23 review threads after confirming they are addressed:

• removed refactor_imports.py
• removed the README Sigma section
• reverted the unchanged PPTX
• standardized Scala/Java conversions through ScalaBridge
• used forEach for signed-input context vars
• combined the ScalaBridge sigma.ast imports

Focused common/libImpl/appkit release-readiness checks passed again on current head. Could you re-review when you have a chance?