Host our own copies of CDN files

base_external.html loads a deleted Rollbar static file - 500s pages extending it

🤖 Written by Claude

## Problem

`uicore/templates/uicore/page/base_external.html` loads Rollbar via:

```
{% static 'js/lib/rollbar/v2.21.1/rollbar.min.js' %}
```

That file no longer exists in source. `rollbar` is absent from `variantgrid/static_files/default_static/js/lib/` in both git and on disk — the only surviving copies are stale artifacts in the gitignored `sitestatic/` collectstatic output on machines that have not re-run collectstatic.

Because `STATICFILES_STORAGE` is `ManifestStaticFilesStorage` and `collectstatic` rewrites `staticfiles.json` from scratch on every run, once a deployment runs collectstatic the entry is gone and `{% static %}` raises `ValueError: Missing staticfiles manifest entry` at template render time. That is a 500 on the page, not merely a missing script tag.

Four templates extend `base_external.html`:

- `snpdb/templates/snpdb/uptime_check.html`
- `classification/templates/classification/evidence_keys.html`
- `mme/templates/mme/mme_metrics.html`
- `mme/templates/mme/mme_disclaimers.html`

`uptime_check` is the one to look at first.

## How it happened

Two commits:

- `68f219e6f` — *"#539 - locally host bootstrap and rollbar"* — moved both `base.html` and `base_external.html` off the CDN onto a vendored copy at `variantgrid/static_files/default_static/js/lib/rollbar/v2.21.1/rollbar.min.js`.
- `f42e1ccc3` — *"Update to Rollbar 3.1.0"* (2026-04-10) — pointed `base.html` back at the CDN at v3.1.0 and deleted the vendored file, while `base_external.html` kept referencing it:

```
uicore/templates/uicore/page/base.html | 2 +-
.../default_static/js/lib/rollbar/rollbar.min.js.map | 1 -
.../default_static/js/lib/rollbar/v2.21.1/rollbar.min.js | 1 -
```

Current state on master:

| template | loads Rollbar from |
|---|---|
| `uicore/page/base.html` | CDN v3.1.0 |
| `uicore/page/base_external.html` | `{% static %}` v2.21.1 (file deleted) |

For reference, the `vg3_sapath_prod` branch is unaffected — it predates both commits and loads CDN v2.21.1 uniformly across all of its config sites.

## Why the test suite does not catch it

`URLTestCase` overrides the storage back to plain `StaticFilesStorage` (`library/django_utils/unittest_utils.py:125`), with a docstring stating that this is precisely because `ManifestStaticFilesStorage` expects `staticfiles.json` to exist and contain the requested file. So URL tests over these pages pass regardless of whether the manifest entry exists.

## Fix

The direction is a decision, since #539 deliberately moved these to local hosting and `f42e1ccc3` moved `base.html` back to the CDN without that being the stated intent:

1. **Match `base.html`** — point `base_external.html` at CDN v3.1.0. One line, and both templates end up consistent.
2. **Restore local hosting** — re-add the vendored file and point both templates at `{% static %}`, which is what #539 was after. Keeps Rollbar working where outbound CDN access is restricted.

Whichever is chosen, both templates should agree.

## Verification

Confirm on a deployment that has run collectstatic since 2026-04-10 whether the four pages above currently return 500. That determines whether this is live breakage or still latent.

Related: #1740 (filtering browser-extension noise out of Rollbar) touches the same `_rollbarConfig` blocks.

Start with uicore/templates/uicore/page/base_external.html and compare its Rollbar reference with uicore/templates/uicore/page/base.html. Inspect the four extending templates, especially snpdb/templates/snpdb/uptime_check.html, and review the static storage behavior described in library/django_utils/unittest_utils.py. Done means both base templates use an available, consistent Rollbar source and the affected pages no longer fail after collectstatic.

Written by the indexing model from the issue text.