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/swarm/api_heartbeat.py

@@ -135,8 +135,8 @@ async def _reconcile_topology_report(
     reported_hash = (reported or {}).get("applied_version_hash")
 
     for topo in mine:
-        tid = topo["id"]
-        if topo.get("needs_resync"):
+        tid = topo.id
+        if topo.needs_resync:
             continue
         expected: Optional[str] = None
         if reported_id == tid and reported_hash: