fix(recovery): register lazy state.db tables in one schema map; cover .recover lane and count-mismatch loss

Follow-up to the salvaged #100350 commits: replace the per-table
'if table == "delivery_obligations"' branches in session_recovery.py and
session_lost_and_found.py with a single _AUXILIARY_TABLE_SCHEMAS registry
(table -> destination DDL initializer) that both the SQL-level and the
lost_and_found lanes consume, so the next lazily-created state.db table is
one entry, not three code paths. The .recover lane now iterates
_CANONICAL_TABLES + _AUXILIARY_TABLES instead of a duplicated literal list.

Tests: the .recover direct-copy lane creates the missing ledger on the
destination; a source-vs-destination obligation count mismatch fails
verification (complete=False) instead of reporting a clean salvage.
Docs: state.db table inventory lists delivery_obligations.

Addresses #100313

website/docs/developer-guide/session-storage.md

@@ -21,9 +21,15 @@ Source file: `hermes_state.py`
 ├── gateway_routing       — Gateway routing metadata
 ├── compression_locks     — Cross-process compression locking
 ├── async_delegations     — Async delegation bookkeeping
+├── delivery_obligations  — Gateway outbox (owed replies); created lazily by gateway/delivery_ledger.py
 └── schema_version        — Single-row table tracking migration state
 ```
 
+`hermes sessions recover` copies the row-bearing tables above into the
+recovered database (FTS indexes and `schema_version` are regenerated), including
+the lazily-created `delivery_obligations` ledger when the source has one — its
+row count is verified like `sessions`/`messages`.
+
 Key design decisions:
 - **WAL mode** for concurrent readers + one writer (gateway multi-platform)
 - **FTS5 virtual table** for fast text search across all session messages