Plugin baselines skip tables that already exist

CHANGELOG.md

@@ -105,6 +105,20 @@ ADR-007 and ADR-002.
   the wrong code. The page index now travels with the page.
 - The back label's dotted preview outline outspecified the print reset and drew
   a dashed rule down the edge of every second card.
+- **`flask plugin upgrade-all` failed a plugin whose tables already existed**
+  ("table securesendsecrets already exists" on the tools plugin). Every
+  post-cutover baseline emitted a plain `op.create_table`, which is correct only
+  while a table's existence and its plugin's Alembic stamp cannot disagree.
+  They can: anything that builds tables from the models stamps nothing, and a
+  run that creates a table then fails before its stamp commits leaves the same
+  split, where re-running is the obvious response. Creates and indexes across
+  all nine table-creating plugin migrations now skip what is already there.
+  Indexes are matched on their COLUMNS rather than their name, because
+  `db.create_all()` names them by SQLAlchemy's convention and a migration by
+  this repo's, so a name-keyed check would silently add a duplicate index
+  instead of skipping. Note the remaining limit: this makes a baseline
+  idempotent, not a whole chain. A longer chain can still meet an `ALTER` whose
+  column is already present, which no guard on `create_table` addresses.
 - **Saving a machine that has a controlling PC answered "this relationship
   already exists" and refused the save.** Reported against a map position
   change, but the map was incidental: the form re-POSTed the controlling-PC