feat(session-query): expose projectSessions batch projection

Public SessionQueryService.projectSessions wraps the existing corpus
projectMany: one persistence listing, bounded persisted-inspect
concurrency, per-id failure isolation, and a synchronous projector over
a borrowed source with no replay validation or cloning.
readTitleSnapshots now routes through it; LogicalSessionSource and
LogicalProjectionResult are exported and documented.

scripts/type-equiv.manifest.json

@@ -449,6 +449,16 @@
       "symbol": "SessionTitleObservationResult",
       "source": "packages/session-query/session-query/src/types.ts"
     },
+    {
+      "doc": "docs/core-data-structures/session-query.md",
+      "symbol": "LogicalSessionSource",
+      "source": "packages/session-query/session-query/src/corpus.ts"
+    },
+    {
+      "doc": "docs/core-data-structures/session-query.md",
+      "symbol": "LogicalProjectionResult",
+      "source": "packages/session-query/session-query/src/corpus.ts"
+    },
     {
       "doc": "docs/core-data-structures/session-query.md",
       "symbol": "SessionEventRecord",