[a-shannon]

Add Zcash address, extraction, and native transaction support

Summary

Add transparent Zcash address handling to the shared codec, a Zebra RPC Rosen
deposit extractor, and bounded native inspector/payment sources with locked Rust
dependencies. The inspector exposes transaction structure without deciding Rosen
admission; the payment primitive constructs and validates exact transparent v5
payments and ZIP-244 digests.

Validation

• Zcash address codec tests, workspace builds, and type checks passed.
• Native inspector and payment suites passed against their locked dependencies and
  documented public fixtures.
• The extractor passed focused RPC/native checks and was consumed by the scanner,
  guard, watcher, and UI candidate graph.

Current native and extraction checks

The extractor now hashes and invokes the native helper asynchronously in bounded
batches (32 transactions and 2 MB of decoded bytes). Ordered, strict native results
remain authoritative even when RPC output projections are malformed. A failure
cannot return a partial batch.

The locked librustzcash pin is 5345dbe0cd6c7f2057e631a34a74dffa84ff1d48.
NU7 branch 77190ad9 is recognized: the inspector covers v5/v6 and rejects v4;
the payment primitive covers v5 construction and actual CHECKSIG, including
rejection of a signature from the previous branch. Payment v6 and post-NU6.2
Orchard remain outside that payment profile.

Current checks: 29 native inspector tests, 24 native payment tests (including
the retained Orchard proof), 11 native wrapper tests and 25 extraction tests;
affected TypeScript/build/lint pass. Independent review covered the exact changes.
These are parser, signature and local consumer checks, not NU7 node admission or
an activation schedule.

Coordination

Coordinating review and all seven PRs.

The cross-repository scope and evidence are recorded in the
Zcash integration review.
The Changesets remain authoritative for versions. Official package/native releases,
consumer lock regeneration, and hosted CI are still required before deployment.