fix(state): escape underscores in the cjk family exclusion LIKE pattern

Review feedback on #103657: the sibling clauses in the same statement
declare ESCAPE, and the trash enumeration two blocks up escapes its
underscores via replace. Use the same escaped ESCAPE form so every
underscore in the statement is a literal match instead of a
single-character wildcard. Behavior on the fixed schema is unchanged
(same enumeration split); this is consistency plus defense against
future lookalike table names.

Also reword the exclusion comment to the verified failure mechanism:
fts5 xRename renames the whole shadow family in one step, so sweeping
the cjk vtable aborts the loop on the next shadow entry and drags the
_config table (read by the vtable constructor) into the trash family.

hermes_state_search.py

@@ -532,9 +532,11 @@ class SessionSearchMixin:
                     "AND (name LIKE 'messages_fts_%' ESCAPE '\\' "
                     "OR name LIKE 'messages_fts_trigram_%' ESCAPE '\\') "
                     # messages_fts_cjk* is an independent v23+ index, not part of the
-                    # demoted legacy layout: renaming it (or its shadow tables) breaks
-                    # the vtable constructor chain (#103647).
-                    "AND name NOT LIKE 'messages_fts_cjk%'"
+                    # demoted legacy layout: fts5's xRename renames the entire shadow
+                    # family in one step, so sweeping the cjk vtable here aborts the
+                    # loop on the next cjk shadow entry and drags _config — needed by
+                    # the vtable constructor — into the trash family (#103647).
+                    "AND name NOT LIKE 'messages\\_fts\\_cjk%' ESCAPE '\\'"
                 ).fetchall():
                     conn.execute(f"ALTER TABLE {row[0]} RENAME TO fts_v22_trash_{row[0]}")
             # Claim the backfill BEFORE the empty v23 tables exist so a crash before