test(dpp): restore ~60 commented-out/ignored tests

[thepastaclaw]

Issue being fixed or feature implemented

Restore ~60 commented-out, ignored, and broken tests in rs-dpp that were silently disabled during API migrations. These tests cover critical paths: signing/validation, serialization, schema validation, and document factory operations.

Tracking issue: thepastaclaw/tracker#12.

What was done?

Nine incremental commits, one per fix area:

1. C-05: Add missing #[test] attributes to schema_defs tests in v0/v1
2. C-11: Fix copy-paste bug testing DocumentTypeV0 instead of DocumentTypeV1 in try_from_schema/v1
3. C-02: Remove #[ignore] from 6 recursive_schema_validator tests
4. C-03: Restore 10 commented-out DataContractV0 serialization tests (updated to current API)
5. C-06: Restore DataContractUpdateTransition JSON conversion test
6. C-04: Restore 5 commented-out DocumentFactory tests (updated to current API)
7. C-01: Restore 19 commented-out signing trait tests (updated to current API)
8. Fix 4 compilation errors against current API (import, type mismatch, missing arg, enum variant)
9. Fix 7 runtime assertion failures (validator behavior changes, missing doc types, JSON serialization)

How Has This Been Tested?

• cargo test -p dpp --lib → 523 passed, 0 failed
• cargo test -p dpp (including doctests) → all pass
• No production code changes — tests only, so no risk of behavioral regression
• Each commit was verified individually to ensure incremental correctness
• All restored tests exercise real code paths (signing, serialization, schema validation, document factory) — no stubs or mocks added

Validation

All DPP-related CI checks pass on the head commit (893becfe):

CI Check	Result	Duration
Rust packages (dpp) / Tests	✅ pass	2m 56s
Rust packages (dpp) / Check each feature	✅ pass	12m 38s
Rust packages (dpp) / Linting	✅ pass	2m 9s
Rust packages (dpp) / Formatting	✅ pass	35s
Rust packages (dpp) / Unused dependencies	✅ pass	1m 47s
Rust packages (dpp) / Detect immutable structure changes	✅ pass	12s

Downstream packages also pass (confirming no ripple effects from test-only changes):

CI Check	Result	Duration
Rust packages (drive) / Tests	✅ pass	7m 41s
Rust packages (drive-abci) / Tests	✅ pass	11m 32s
Rust packages (dash-sdk) / Tests	✅ pass	3m 35s
Rust packages (wasm-dpp) / Tests	✅ pass	2m 9s

Two pre-existing CI failures unrelated to this PR:

• JS NPM security audit — known base-branch issue
• Swift SDK build — known missing symbols issue (tracked in platform#3107)

Local validation (pre-push):

• cargo test -p dpp --lib — 523 tests passed, 0 failed
• cargo test -p dpp (full, including doctests) — all pass
• Each of the 9 commits verified individually for incremental correctness

Breaking Changes

None. This PR contains only test code changes.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone