feat: convert tmux monitoring into a plugin (B10)

drizzle/mysql/0039_condemned_shiva.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/mysql/meta/_journal.json

@@ -274,6 +274,13 @@
       "when": 1790208810478,
       "tag": "0038_quiet_karnak",
       "breakpoints": true
+    },
+    {
+      "idx": 39,
+      "version": "5",
+      "when": 1790220944905,
+      "tag": "0039_condemned_shiva",
+      "breakpoints": true
     }
   ]
 }