session-memory: map signals to catalog recommendations via covers (WP-0010 follow-up)

Closes the gap where recurring_error suggestions showed generic 'Investigate'
instead of the curated recommendation. Added a covers[] field to SolutionPattern
(lowercase substrings a pattern's recommendation also applies to) + Catalog.find_for
(exact key first, then covers match against signal key+locus). Retro now resolves
recommendations through find_for. Tagged the read-before-edit pattern with
covers=['file has not been read','modified since read','file_not_read'] (v1.0.1).
Live: file-not-read suggestions across all repos now inherit 'Read the file before
Edit/Write'. 6 new tests; suite 158/158.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

session_memory/catalog/sp-problem-file_not_read-edit.json

@@ -1,4 +1,9 @@
 {
+  "covers": [
+    "file has not been read",
+    "modified since read",
+    "file_not_read"
+  ],
   "created_at": "2026-06-07T13:26:25Z",
   "distribution_ready": true,
   "id": "sp-problem-file_not_read-edit",
@@ -53,6 +58,6 @@
     "repos": []
   },
   "status": "approved",
-  "updated_at": "2026-06-07T13:26:25Z",
-  "version": "1.0.0"
+  "updated_at": "2026-06-07T19:06:45Z",
+  "version": "1.0.1"
 }