fix: address review round two

- listChildren contains per-child projection faults on both ladder rungs
  (any registered unit's fold/schema rejection maps to that child's corrupt
  diagnostic) and pins the whole-enumeration listing-failure rethrow
- the base bundle mounts session-projection (web-app's own insert retired
  to avoid the double mount); stale composition comment updated
- the shared projections-unavailable wire face is pinned across
  list/history/prompt; retired session-query arms removed from the catalog
  paths
- the design note records the unknown-parent semantics shift and the
  fold-fault isolation rule

apps/cli/composition.md

@@ -40,6 +40,8 @@ flowchart LR
   cfg --> plugin_dsh_base_session_persistence_jsonl
   plugin_dsh_base_session_query_sqlite["session-query-sqlite<br/>@deepseek-ai/dsh-session-query-sqlite"]
   cfg --> plugin_dsh_base_session_query_sqlite
+  plugin_dsh_base_session_projection["session-projection<br/>@deepseek-ai/dsh-session-projection"]
+  cfg --> plugin_dsh_base_session_projection
   plugin_dsh_base_telemetry_otel["telemetry-otel<br/>@deepseek-ai/dsh-session-telemetry-otel"]
   cfg --> plugin_dsh_base_telemetry_otel
   plugin_dsh_base_subprocess["subprocess<br/>@deepseek-ai/dsh-subprocess-local"]
@@ -166,6 +168,7 @@ flowchart LR
 | `llm-pi-ai` | `@deepseek-ai/dsh-llm-pi-ai` |
 | `session-persistence-jsonl` | `@deepseek-ai/dsh-session-persistence-jsonl` |
 | `session-query-sqlite` | `@deepseek-ai/dsh-session-query-sqlite` |
+| `session-projection` | `@deepseek-ai/dsh-session-projection` |
 | `telemetry-otel` | `@deepseek-ai/dsh-session-telemetry-otel` |
 | `subprocess` | `@deepseek-ai/dsh-subprocess-local` |
 | `sandbox` | `@deepseek-ai/dsh-sandbox-local` |