feat(dpp): add documents_countable and blast_syncable to DocumentTypeV2

Adds two new fields to DocumentTypeV2:

- `documents_countable: bool` — primary key tree uses CountTree for
  O(1) total document count queries
- `blast_syncable: bool` — primary key tree uses ProvableCountTree
  for BLAST sync support. Implies documents_countable = true.

Changes:
- DocumentTypeV2 struct with both fields
- V2 variant added to DocumentType/DocumentTypeRef/DocumentTypeMutRef
- DocumentTypeV2Getters/Setters traits
- Schema parsing v2 with protocol version 12+ gating
- Drive: CountTree for countable, ProvableCountTree for blast_syncable
- Meta-schema: documentsCountable and blastSyncable properties
- Fix duplicate V2 match arms (clippy unreachable-patterns)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: QuantumExplorer

packages/rs-dpp/schema/meta_schemas/document/v0/document-meta.json

@@ -505,6 +505,14 @@
       ],
       "description": "Key requirements. 0 - Unique Non Replaceable, 1 - Multiple, 2 - Multiple with reference to latest key."
     },
+    "documentsCountable": {
+      "type": "boolean",
+      "description": "When true, the primary key tree uses a CountTree enabling O(1) total document count queries"
+    },
+    "blastSyncable": {
+      "type": "boolean",
+      "description": "When true, the primary key tree uses a ProvableCountTree enabling BLAST sync. Implies documentsCountable."
+    },
     "tokenCost": {
       "type": "object",
       "properties": {