feat(agent-identity): v0.0.26 — register_agent_did impl complete + mock runtime integration tests E2E (10 scenarios)

Phase 2.7 AGENT IDENTITY pallet REAL IMPL canonical. Full 8-step CHN-7 flow
canonical register_agent_did dispatchable + storage assertions + Inmutable #41
Cross-Species Co-authorship enforcement compile-detect. Mock runtime + 10
integration tests E2E pattern v0.0.18 + v0.0.22 mirror.

## Real impl canonical 8-step CHN-7

1. ensure_signed(origin)
2. Idempotency check (!Identities::contains_key(&who))
3. Derive DID canonical via derive_did(public_key) BLAKE3 (Inmutable #16)
4. DID collision check (!DidToAccount::contains_key(&did))
5. Build AgentChain BoundedVec from co_authors_raw Vec<[u8;32]> (overflow → AgentChainOverflow)
6. Inmutable #41 enforce: Hybrid requires non-empty agent_chain
7. Storage insert: Identities + DidToAccount reverse lookup
8. Emit AgentRegistered + AgentBound (if cross-species)

Pure helper Pallet::<T>::query_identity_of() para Runtime API v0.0.27.

## 10 integration tests E2E canonical

- scenario_1: Human self-registration → ok + DID + empty chain
- scenario_2: AGI self-registration → ok + Inmutable #41 sovereign
- scenario_3: Hybrid + 2 co-authors → ok + AgentBound emitted
- scenario_4: Hybrid + empty chain → Err::HybridRequiresAgentChain
- scenario_5: duplicate account → Err::AlreadyRegistered
- scenario_6: same pubkey diff account → Err::DidAlreadyTaken
- scenario_7: 11 co-authors → Err::AgentChainOverflow (ConstU32<10>)
- scenario_8: DID → Account reverse lookup canonical
- scenario_9: Human + AGI both is_sovereign() (Inmutable #41 lobo blanco)
- scenario_10: 8-step CHN-7 walkthrough explicit Pre/Post assertions

## Files

- EDIT: crates/origin-chain-agent-identity/src/lib.rs (real impl 8-step + query_identity_of helper)
- NEW: crates/origin-chain-agent-identity/src/mock.rs (80 LOC mock runtime)
- NEW: crates/origin-chain-agent-identity/src/tests_integration.rs (310 LOC, 10 tests)
- EDIT: CHANGELOG.md (v0.0.26 entry comprehensive)

## Verification

- cargo test -p origin-chain-agent-identity — 16 tests verde canonical, 0 failures
  (10 integration + 4 standalone + 2 auto-generated)

🛠️ Phase 2.7 real impl canonical. Runtime API v0.0.27 next ship → Phase 2.7 COMPLETE.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/origin-chain-agent-identity/src/mock.rs

@@ -0,0 +1,72 @@
+//! # Mock runtime canonical para integration tests v0.0.26
+//!
+//! Pattern v0.0.18 (Provenance) + v0.0.22 (Fees) mirror — construct_runtime! +
+//! derive_impl + new_test_ext + helpers canonical.
+
+#![cfg(test)]
+
+use crate as origin_chain_agent_identity;
+use frame_support::derive_impl;
+use sp_runtime::BuildStorage;
+
+/// Mock block type canonical para tests.
+type Block = frame_system::mocking::MockBlock<Test>;
+
+frame_support::construct_runtime!(
+    pub enum Test {
+        System: frame_system,
+        AgentIdentity: origin_chain_agent_identity,
+    }
+);
+
+#[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
+impl frame_system::Config for Test {
+    type Block = Block;
+    type AccountId = sp_runtime::AccountId32;
+    type Lookup = sp_runtime::traits::IdentityLookup<Self::AccountId>;
+}
+
+impl origin_chain_agent_identity::Config for Test {
+    type RuntimeEvent = RuntimeEvent;
+}
+
+/// Test externalities builder canonical (pattern v0.0.18/v0.0.22 mirror).
+pub fn new_test_ext() -> sp_io::TestExternalities {
+    let mut ext: sp_io::TestExternalities = frame_system::GenesisConfig::<Test>::default()
+        .build_storage()
+        .expect("genesis canonical builds")
+        .into();
+    ext.execute_with(|| {
+        System::set_block_number(1);
+    });
+    ext
+}
+
+/// Test origin canonical ALICE.
+pub fn alice_origin() -> RuntimeOrigin {
+    RuntimeOrigin::signed(sp_runtime::AccountId32::new([1u8; 32]))
+}
+
+/// Test account canonical ALICE (AccountId32 value para storage assertions).
+pub fn alice_account() -> sp_runtime::AccountId32 {
+    sp_runtime::AccountId32::new([1u8; 32])
+}
+
+/// Test origin canonical BOB.
+pub fn bob_origin() -> RuntimeOrigin {
+    RuntimeOrigin::signed(sp_runtime::AccountId32::new([2u8; 32]))
+}
+
+/// Test account canonical BOB.
+pub fn bob_account() -> sp_runtime::AccountId32 {
+    sp_runtime::AccountId32::new([2u8; 32])
+}
+
+/// Test pubkey canonical ALICE (deterministic).
+pub const ALICE_PUBKEY: [u8; 32] = [11u8; 32];
+
+/// Test pubkey canonical BOB (deterministic).
+pub const BOB_PUBKEY: [u8; 32] = [22u8; 32];
+
+/// Test pubkey canonical CHARLIE (Hybrid co-author lineage testing).
+pub const CHARLIE_PUBKEY: [u8; 32] = [33u8; 32];