feat: add NuTachyon and V7 transactions

[S1nus]

The bulk of Tachyon’s logic is tachyon::coherence (semantic verification), TachyonMiningData in the state service, and the get_block_template handler in RPC, update_chain_tip_with_block_parallel in crates/zakura-state/src/service/non_finalized_state/chain.rs; the rest of the PR is mostly plumbing.

zakura-chain

• Adds a cfg-gated zakura_chain::tachyon module containing wrappers for Tachyon’s Anchor and Tachygram types.
• Updates V4 history tree computation to hash the Tachyon anchor into the tree.
• Adds the NuTachyon NetworkUpgrade, ConsensusBranchId, and TX_V7_VERSION_GROUP_ID.
• Adds the V7 transaction type, which carries Tachyon bundles.
• Updates value balance calculation to include Tachyon bundles.
• Adds tachyon_anchor and tachyon_epoch_anchor to NoteCommitmentTrees.

zakura-consensus

• Modifies the mempool transaction verifier to enforce valid digests for Tachyon actions and accept only autonome transactions for now. In the future, we will perform peer-to-peer aggregation and allow other kinds of Tachyon transactions to propagate through the mempool.
• Adds parallelized validation of Tachyon signatures.
• Adds proof stamp verification.
• Adds error types for Tachyon’s invariants.
• Adds Tachyon coherence checks to semantic block verification.

zakura-network

• Updates CURRENT_NETWORK_PROTOCOL_VERSION_VALUE.
• Adds NuTachyon and V7 transaction arms to exhaustive match statements in tests.

zakura-state

• Adds tachyon_anchor and tachyon_epoch_anchor to TreeState.
• Updates ChainInner with Tachyon anchors, epoch anchors, tachygrams, and their height/epoch indexes.
• Executes Tachyon transactions while updating the chain tip in parallel.
• Adds TachyonMiningData to the read state service so miners can retrieve anchor data and revealed tachygrams for aggregation during block construction.
• Adds contextual transaction verification for nullifiers and anchors.
• Updates the database version and adds four finalized-state column families for Tachyon anchors, anchor indexes, epoch anchors, and tachygrams.
• Filters Tachyon-enabled blocks from VCT roots in commit_finalized_direct_with_aux (we may want to revisit how Tachyon affects VCT).
• Verifies Tachyon commitment roots.
• Updates history tree computation.
• Adds helpers to store and prune tachygrams.

zakura-rpc

• Updates get_block_template so miners aggregate autonome transactions from the mempool.
• Adds aggregation logic under zakura-rpc/src/methods/types/get_block_template/tachyon.rs.

Validation

• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 check --locked -p zakura-chain -p zakura-consensus -p zakura-state -p zakura-rpc --all-targets
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 test --locked -p zakura-chain
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 test --locked -p zakura-consensus tachyon
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 test --locked -p zakura-state tachyon
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 clippy --locked -p zakura-chain -p zakura-consensus -p zakura-state -p zakura-rpc --all-targets --no-deps -- -D warnings
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" RUSTFLAGS='' cargo +1.91.0 check --locked -p zakura-chain -p zakura-consensus -p zakura-state -p zakura-rpc --all-targets
• Generated empty, Adjunct, single-action Proven, and multi-action Proven V7 vectors match the exact fixtures in feat: add NuTachyon support to forked librustzcash crates common#178.
• Formatting, Markdown lint, locked metadata, and changelog policy checks.

[S1nus]

Follow-up validation for d5fce97:

• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 test -p zakura-rpc nu_tachyon_template_converts_to_proposal_block
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 clippy -p zakura-rpc --all-targets -- -D warnings
• cargo fmt --all -- --check
• ./scripts/changelog.py check

The regression test constructs a NuTachyon block template, converts it through the internal-miner proposal path, and verifies the header uses the block-commitments hash.

[S1nus]

Validation for 96cea46: cargo fmt --all -- --check; cargo +1.97.1 clippy -p zakura-rpc --all-targets -- -D warnings; cargo +1.97.1 test -p zakura-rpc; RUSTFLAGS= cargo +1.91.0 check --locked -p zakura-rpc --all-targets; ./scripts/changelog.py check. Cargo commands used ROCKSDB_LIB_DIR=/opt/homebrew/lib.

[S1nus]

Validation for a871092: cargo fmt --all -- --check; cargo +1.97.1 clippy -p zakura-state -p zakura-rpc --all-targets -- -D warnings; cargo +1.97.1 test -p zakura-state tachyon; cargo +1.97.1 test -p zakura-rpc get_block_template::tachyon::tests; RUSTFLAGS= cargo +1.91.0 check --locked -p zakura-state -p zakura-rpc --all-targets; ./scripts/changelog.py check. Cargo commands used ROCKSDB_LIB_DIR=/opt/homebrew/lib.

[S1nus]

Added structured Tachyon bundle data to verbose getblock / getrawtransaction transaction objects, including actions, balances, memo, signatures, proof stamps, and adjunct aggregate IDs.

Validation:

• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 fmt --all -- --check
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 clippy -p zakura-rpc --all-targets -- -D warnings
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" cargo +1.97.1 test -p zakura-rpc --lib (134 passed, 1 ignored)
• ROCKSDB_LIB_DIR="/opt/homebrew/lib" RUSTFLAGS="" cargo +1.91.0 check --locked -p zakura-rpc --all-targets
• ./scripts/changelog.py check