feat: convert tmux monitoring into a plugin (B10)

drizzle/postgres/0040_narrow_hellion.sql

@@ -0,0 +1,5 @@
+-- tmux_session_tags moved to the tmux-monitor plugin, whose first migration
+-- renames it to p_tmux_monitor_session_tags. Dropping it here would lose
+-- every saved tag, so this only stops drizzle tracking it. SELECT 1 because
+-- MySQL rejects an empty query.
+SELECT 1;

drizzle/postgres/meta/_journal.json

@@ -281,6 +281,13 @@
       "when": 1790208809860,
       "tag": "0039_violet_firedrake",
       "breakpoints": true
+    },
+    {
+      "idx": 40,
+      "version": "7",
+      "when": 1790220944274,
+      "tag": "0040_narrow_hellion",
+      "breakpoints": true
     }
   ]
 }