Commit the first migration, and apply schema the same way everywhere

`drizzle/` was gitignored, so every environment re-derived the schema from
src/db/schema and nothing recorded what a given release expected. That is
survivable while nothing is deployed and a problem the moment something is.
The generated migration is now committed: four tables, three enums, five
foreign keys, and the per-farm unique index on gateway_printer_id.

It needed one hand-added line to be usable on its own. drizzle-kit does not
emit extension statements, but frame_embeddings.embedding is vector(512) with
an ivfflat index, so as generated the migration only applied to a database
somebody had already run `CREATE EXTENSION vector` on - which was true locally
precisely because dev-env.sh does that, and would not have been true on a
fresh deploy. `CREATE EXTENSION IF NOT EXISTS vector` now leads the file, and
it survives regeneration: drizzle only appends new migrations, and the diffing
snapshot lives in meta/0000_snapshot.json rather than in the SQL.

Verified by dropping the database, recreating it with no extensions at all
(`pg_extension` count 0), and running db:migrate: the extension and all four
tables were created, `db:generate` then reported no pending changes, and the
e2e script still passed against both live printers on the result.

`dev-env.sh schema` now runs `migrate` instead of `push`, so a local database
and a deployed one get the schema by the same route - testing `push` locally
while production runs `migrate` tests two different things. `push` is still
available as its own command for iterating on a table that is still moving,
with a comment about what it does not record.

drizzle/meta/_journal.json

@@ -0,0 +1,13 @@
+{
+  "version": "7",
+  "dialect": "postgresql",
+  "entries": [
+    {
+      "idx": 0,
+      "version": "7",
+      "when": 1791029521420,
+      "tag": "0000_watery_firedrake",
+      "breakpoints": true
+    }
+  ]
+}