registry: add extension migration seam

TASKS.md

@@ -148,4 +148,5 @@ Progress:
   - Phase 0 / task `0.5`: введены `PolicyEngine`, `SessionActor`, `PolicyAction`, `PolicyScope`, `PolicyDecision` и default `OwnerOnlyPolicyEngine` в public seam `crank_core::ext::access`
   - Phase 0 / task `0.6`: введены `AuditSink`, `NoopAuditSink`, `AuditEventId` и базовые audit-типы в public seam `crank_core::ext::audit`
   - Phase 0 / task `0.7`: введены `CapabilityProfile` и `CommunityCapabilityProfile`, а `admin-api` capability payload теперь собирается через public seam вместо локального literal
+  - Phase 0 / task `0.13`: введены `RegistryExtension`, `ExtensionMigration` и `apply_extension_migrations(...)` в `crank-registry` как отдельный public seam для additive private migrations
   - backward-compatible alias `CommunityMachineCredentialVerifier` сохранен, поведение Community не изменено

crates/crank-registry/src/ext.rs

@@ -0,0 +1,77 @@
+use std::sync::Arc;
+
+use sqlx::{PgPool, query};
+
+use crate::RegistryError;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct ExtensionMigration {
+    pub version: u32,
+    pub sql: &'static str,
+}
+
+pub trait RegistryExtension: Send + Sync {
+    fn name(&self) -> &str;
+    fn migrations(&self) -> &[ExtensionMigration];
+}
+
+pub async fn apply_extension_migrations(
+    pool: &PgPool,
+    extensions: &[Arc<dyn RegistryExtension>],
+) -> Result<(), RegistryError> {
+    query(
+        "create table if not exists __crank_ext_migrations (
+            extension_name text not null,
+            version integer not null,
+            applied_at timestamptz not null default now(),
+            primary key (extension_name, version)
+        )",
+    )
+    .execute(pool)
+    .await?;
+
+    for extension in extensions {
+        for migration in extension.migrations() {
+            let already_applied = query(
+                "select 1
+                 from __crank_ext_migrations
+                 where extension_name = $1 and version = $2",
+            )
+            .bind(extension.name())
+            .bind(i32::try_from(migration.version).map_err(|_| {
+                RegistryError::InvalidNumericValue {
+                    field: "extension_migration.version",
+                    value: migration.version as i64,
+                }
+            })?)
+            .fetch_optional(pool)
+            .await?
+            .is_some();
+
+            if already_applied {
+                continue;
+            }
+
+            let mut tx = pool.begin().await?;
+
+            query(migration.sql).execute(&mut *tx).await?;
+            query(
+                "insert into __crank_ext_migrations (extension_name, version)
+                 values ($1, $2)",
+            )
+            .bind(extension.name())
+            .bind(i32::try_from(migration.version).map_err(|_| {
+                RegistryError::InvalidNumericValue {
+                    field: "extension_migration.version",
+                    value: migration.version as i64,
+                }
+            })?)
+            .execute(&mut *tx)
+            .await?;
+
+            tx.commit().await?;
+        }
+    }
+
+    Ok(())
+}

crates/crank-registry/src/lib.rs

@@ -1,9 +1,11 @@
 mod error;
+mod ext;
 mod migrations;
 mod model;
 mod postgres;
 
 pub use error::RegistryError;
+pub use ext::{ExtensionMigration, RegistryExtension, apply_extension_migrations};
 pub use model::{
     AgentSummary, AgentVersionRecord, AsyncJobFilter, AsyncJobRecord, AuthUserRecord,
     CreateAgentRequest, CreateAsyncJobRequest, CreateInvitationRequest, CreateInvocationLogRequest,