Let a super admin read the database from the app

A new super admin settings page, /admin/settings/database, lists every
table with its record count and size, and one page of the open table's
records newest key first. Values are cut inside SQL (400 characters, with
a flag saying so) and a record opens whole in a modal, so a table of long
texts reads without shipping it all. A search matches every column's
text, word by word or as a phrase, which is the one thing that also works
on a virtual table. Nothing in it writes: the catalog, the records and
the single record are all reads, GET only.

src/functions/backend/database/build-table-sizes-sql.ts

@@ -0,0 +1,19 @@
+/**
+ * How many bytes each table takes on disk. `dbstat` reports pages per
+ * b-tree; an index's pages are named after the index (`autoindex` or the
+ * schema's own), so the join puts them back under the table they belong
+ * to. A table with no pages yet has no row here.
+ */
+export default function buildTableSizesSql(): string {
+    return `SELECT
+        COALESCE(i.tbl_name, d.name) AS table_name,
+        SUM(d.pgsize) AS bytes
+    FROM dbstat AS d
+    LEFT JOIN sqlite_master AS i ON i.type = 'index' AND i.name = d.name
+    GROUP BY COALESCE(i.tbl_name, d.name)`;
+}
+
+export type TableSizeRow = {
+    table_name: string;
+    bytes: number;
+};