Add support for ГОСТ Р 34.10 digital signatures

- Implemented the GostKeyValue class for handling public key parameters in ГОСТ Р 34.10 digital signatures.
- Created the GostSignedXml class to manage XML signatures using ГОСТ 34.10, including methods for computing and checking signatures.
- Developed the GostSignedXmlImpl class to encapsulate the signature computation logic and public key retrieval.
- Added specific key value classes for ГОСТ Р 34.10-2001, ГОСТ Р 34.10-2012/256, and ГОСТ Р 34.10-2012/512 to support different signature algorithms.
- Ensured compatibility with existing XML signature standards while integrating ГОСТ cryptography.

docs/modules/vex-lens/implementation_plan.md

@@ -15,11 +15,11 @@
 ## Work breakdown
 - **VEX Lens service**
   - Normalise VEX payloads, maintain scope scores, compute consensus digest.
-  - Trust weighting functions (issuer tier, freshness decay, scope quality).
+  - Trust weighting functions (issuer tier, freshness decay, scope quality) ingest the new `vex.provenance.*` contract emitted by Excititor connectors (provider weight/tier, cosign metadata, fingerprints) so connector-tuned trust flows all the way to consensus.
   - Idempotent workers for consensus projection and history tracking.
   - Conflict handling queue for manual review and notifications.
 - **Integrations**
-  - Excitor: enrich VEX events with issuer hints, signatures, product trees.
+  - Excitor: enrich VEX events with issuer hints, signatures, product trees, and now connector-supplied trust weights/tiers that Lens consumes directly.
   - Policy Engine: trust knobs, simulation endpoints, policy-driven recompute.
   - Vuln Explorer & Advisory AI: consensus badges, conflict surfacing.
 - **Issuer Directory**