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.

decnet/web/router/topology/api_deploy_topology.py

@@ -63,11 +63,11 @@ async def api_deploy_topology(
     topo = await repo.get_topology(topology_id)
     if topo is None:
         raise HTTPException(status_code=404, detail="Topology not found")
-    if topo["status"] != TopologyStatus.PENDING:
+    if topo.status != TopologyStatus.PENDING:
         raise HTTPException(
             status_code=409,
             detail=(
-                f"Topology is {topo['status']!r}; only 'pending' topologies "
+                f"Topology is {topo.status!r}; only 'pending' topologies "
                 f"can be deployed."
             ),
         )