refactor(topology): introduce TopologyRepository protocol with DTO return types

Replace repo: BaseRepository with a structural TopologyRepository protocol
in persistence.py and allocator.py. All read methods now return typed DTOs
(TopologySummary, LANRow, DeckyRow, EdgeRow) instead of raw dicts, eliminating
silent field-shape regressions across the topology subsystem.

TopologySummary gains email_personas and language_default so api_personas.py
can continue reading those fields via attribute access. hydrate() converts
DTOs to dicts before passing to _backfill_decky_configs, keeping the mutable
working-state function dict-based at its boundary. All production callers
(router handlers, mutator, CLI, heartbeat) migrated from dict/get access to
attribute access. 134 tests pass.

tests/topology/test_deploy_agent_branch.py

@@ -112,7 +112,7 @@ async def test_deploy_on_agent_routes_via_agent_client(repo, fake_agent) -> None
     assert version_hash == canonical_hash(hydrated)
 
     topo = await repo.get_topology(tid)
-    assert topo["status"] == TopologyStatus.ACTIVE
+    assert topo.status == TopologyStatus.ACTIVE
 
 
 @pytest.mark.anyio
@@ -132,7 +132,7 @@ async def test_deploy_on_agent_failure_marks_failed(repo, monkeypatch) -> None:
         await _deployer.deploy_topology(repo, tid)
 
     topo = await repo.get_topology(tid)
-    assert topo["status"] == TopologyStatus.FAILED
+    assert topo.status == TopologyStatus.FAILED
 
 
 @pytest.mark.anyio
@@ -165,4 +165,4 @@ async def test_teardown_on_agent_routes_via_agent_client(repo, fake_agent) -> No
     assert inst.calls == [("teardown", (tid,), {})]
 
     topo = await repo.get_topology(tid)
-    assert topo["status"] == TopologyStatus.TORN_DOWN
+    assert topo.status == TopologyStatus.TORN_DOWN