feat(runtime-apis): Phase 1.6 — Runtime APIs canonical foundation v0.0.8

Runtime canonical ahora expone 11 APIs foundational via impl_runtime_apis!
macro necesarias para origin-chain-node binary interactuar via sc-service.

## Decisión canonical empírica: pallet_identity DEFERRED a Phase 2.7

pallet-identity 41.0.0 (stable2512) usa ReservableCurrency trait deprecated en
stable2512 (replaced por fungible::Mutate). Compat work es scope Phase 2.7
cuando custom pallet_agent_identity introduce AGI DIDs (Inmutable #41).

Wallet creation FREE perpetua per Inmutable #37 YA materializado via
pallet_balances — account existe con 1 MILLI_OGC EXISTENTIAL_DEPOSIT.
Identity metadata (name + email + GitHub + avatar) viene Phase 2.7.

## 11 APIs canonical implementadas
- sp_api::Core (version + execute_block + initialize_block)
- sp_api::Metadata (runtime metadata canonical)
- sp_block_builder::BlockBuilder (apply_extrinsic + finalize_block + inherents)
- sp_transaction_pool::TaggedTransactionQueue (validate_transaction)
- sp_offchain::OffchainWorkerApi (offchain_worker)
- sp_session::SessionKeys (generate + decode_into_raw_public_keys)
- sp_consensus_aura::AuraApi (slot_duration + authorities)
- sp_consensus_grandpa::GrandpaApi (grandpa_authorities + current_set_id +
  equivocation stubs Phase 1 PoA returning None)
- frame_system_rpc_runtime_api::AccountNonceApi (account_nonce)
- pallet_transaction_payment_rpc_runtime_api::TransactionPaymentApi
  (query_info + query_fee_details + query_weight_to_fee + query_length_to_fee)
- sp_genesis_builder::GenesisBuilder (build_state + get_preset + preset_names)

## Foundation types nuevos canonical
- pub const VERSION: RuntimeVersion canonical (consumed por sp_api::Core::version)
  - spec_name "origin-chain" + impl_name "origin-chain-charon"
  - apis RUNTIME_API_VERSIONS auto-generado por macro
  - state_version 1 (stable2509+ canonical)
- pub type Executive = frame_executive::Executive<...> wrapper canonical

## Compile fix iteración
EquivocationProof type signature: cambió de <Hash, Header> a <Hash, BlockNumber>
canonical per trait signature stable2512. Doc clarifies Phase 1 PoA equivocation
returns None — Phase 2 NPoS introduce real per CHN-3 slashing.

## Build + tests
- cargo check 0.75s warm cache (impl_runtime_apis incremental)
- cargo build --release 9.23s warm cache clean
- ~57 tests passing

## Filosofía canonical
Doc impl_runtime_apis cita David canon 2026-05-14 "la libertad infinita acota
solo donde empieza la del otro" — APIs son la frontera canonical entre runtime
sovereignty + node sovereignty. Forkless upgrades materializados.

## Phase 1 progress
1.1 ✅ + 1.2 ✅ + 1.3 ✅ + 1.4 ✅ + 1.5 ✅ + 1.6 ✅ (esta). Next: 1.7
genesis chain_spec.rs BM V2 allocation (40/25/15/15/5) + origin-chain-node
real Substrate service multi-session work.

Origin Chain runtime canonical actual: 7 pallets + 11 Runtime APIs + Executive
+ RuntimeVersion + opaque SessionKeys = foundation completa para node binary.

Refs: CHARON_ROADMAP_V1 Phase 1.6, Decisión empírica pallet_identity defer,
SBS-4 ratified, arkhe-origin-chain commit pending tag v0.0.8

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/origin-chain-runtime/Cargo.toml

@@ -44,6 +44,17 @@ pallet-grandpa.workspace = true
 # FRAME pallets Phase 1.5 — Session rotation per CHN-1 4h epochs
 pallet-session.workspace = true
 
+# pallet-identity DEFERRED a Phase 2.7 (canonical decision empírica 2026-05-21)
+# pallet-identity.workspace = true
+
+# RuntimeAPI canonical (sp_api::impl_runtime_apis! consumers)
+sp-offchain.workspace = true
+sp-genesis-builder.workspace = true
+sp-transaction-pool.workspace = true
+sp-session.workspace = true
+frame-system-rpc-runtime-api.workspace = true
+pallet-transaction-payment-rpc-runtime-api.workspace = true
+
 # SCALE codec canonical
 parity-scale-codec.workspace = true
 scale-info.workspace = true
@@ -76,6 +87,12 @@ std = [
     "pallet-aura/std",
     "pallet-grandpa/std",
     "pallet-session/std",
+    "sp-offchain/std",
+    "sp-genesis-builder/std",
+    "sp-transaction-pool/std",
+    "sp-session/std",
+    "frame-system-rpc-runtime-api/std",
+    "pallet-transaction-payment-rpc-runtime-api/std",
     "parity-scale-codec/std",
     "scale-info/std",
     "serde",