ci(v1): re-enable the Playwright suite on v1/main

`e2e_tests.yml` filtered on `branches: [main]` for both `push` and
`pull_request` — the same leftover as main.yml, but with a sharper
consequence: `main` never matches on this branch, so the filter matched
nothing and the suite has never run on `v1/main` at all. The branch's full
run history contains zero `Playwright Tests` runs, only
`Run install, format, lint, build, and test on every push` and `CLI Tests`.

Repointed both filters at `v1/main` so the gate actually gates. Unlike the
main.yml change this is a real behavior change — it turns a dead workflow
back on — so it is deliberately a separate commit.

Refs #2065

Signed-off-by: cliffhall <cliff@futurescale.com>

Author: cliffhall

.github/workflows/e2e_tests.yml

@@ -1,10 +1,14 @@
 name: Playwright Tests
 
+# Pinned to `v1/main`, this branch's own base. These filters read `main`
+# historically, from when the v1 line was itself `main` — which meant they
+# matched nothing here and the suite silently never ran on this branch.
+# See #2065.
 on:
   push:
-    branches: [main]
+    branches: [v1/main]
   pull_request:
-    branches: [main]
+    branches: [v1/main]
 
 jobs:
   test: