Implement SAND-WP-0002 meta-framework foundation (T01–T09)

Add meta-framework spec, pydantic schemas, profile/extension YAML, extension
registry, ext.compose-ssh backend, SandboxManager with State Hub events, CLI
commands, integration docs, capability registry entry, and compose-e2e runbook.
Nine unit tests pass. T10 remote smoke test remains for operator.

tests/test_manager.py

@@ -0,0 +1,84 @@
+"""SandboxManager unit tests with mocked backend."""
+
+from __future__ import annotations
+
+from datetime import UTC, datetime
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+from sandboxer.core.manager import SandboxManager
+from sandboxer.lifecycle.store import SandboxStore
+from sandboxer.models import ActorType, Consumer, SandboxCreateRequest, SandboxState, SandboxStatus
+
+
+class FakeBackend:
+    def provision(self, profile, inputs, host):
+        return {
+            "sandbox_id": "test1234",
+            "host": host,
+            "remote_dir": "/tmp/sandboxer/test1234",
+            "compose_project": "sbx-e2e-test1234",
+            "compose_file": "docker-compose.yml",
+            "ssh_user": "root",
+        }
+
+    def wait_ready(self, handle):
+        return {
+            "ssh": f"root@{handle['host']}",
+            "remote_dir": handle["remote_dir"],
+            "compose_project": handle["compose_project"],
+            "host": handle["host"],
+        }
+
+    def teardown(self, handle):
+        return {
+            "compose_removed": "True",
+            "remote_dir_removed": "True",
+            "remote_dir": handle["remote_dir"],
+        }
+
+
+@pytest.fixture
+def store(tmp_path: Path) -> SandboxStore:
+    return SandboxStore(path=tmp_path / "sandboxes.json")
+
+
+def test_create_and_destroy(store: SandboxStore) -> None:
+    manager = SandboxManager(store=store)
+    request = SandboxCreateRequest(
+        profile="profile.compose-e2e",
+        inputs={"repo": "/tmp/repo"},
+        consumer=Consumer(actor=ActorType.ADM, project="sand-boxer"),
+    )
+
+    with (
+        patch("sandboxer.core.manager.resolve_backend", return_value=FakeBackend()),
+        patch("sandboxer.core.manager.emit_lifecycle_event", return_value=None),
+        patch("sandboxer.core.manager.resolve_host", return_value="coulombcore"),
+    ):
+        status = manager.create(request)
+        assert status.state == SandboxState.READY
+        assert status.sandbox_id == "test1234"
+
+        destroyed = manager.destroy(status.sandbox_id)
+        assert destroyed.state == SandboxState.DESTROYED
+
+
+def test_destroy_idempotent(store: SandboxStore) -> None:
+    now = datetime.now(UTC)
+    status = SandboxStatus(
+        sandbox_id="gone1234",
+        profile_id="profile.compose-e2e",
+        extension_id="ext.compose-ssh",
+        state=SandboxState.DESTROYED,
+        consumer=Consumer(actor=ActorType.ADM, project="sand-boxer"),
+        created_at=now,
+        updated_at=now,
+        destroyed_at=now,
+    )
+    store.save(status)
+    manager = SandboxManager(store=store)
+    result = manager.destroy("gone1234")
+    assert result.state == SandboxState.DESTROYED