ci: run the freesailarr install-test for real instead of skipping it

freesailarr was excluded from the install-test because gluetun never becomes
healthy without a real Wireguard key and no app container behind its kill
switch can become Ready. The green "Install-test freesailarr pass" was a
25-second SKIP on the most complex chart in the repo - a signal that proved
nothing.

With a CI-only Mullvad key in 1Password the reason is gone:

- ci/run-install-test.sh learns a general rule: ci/<chart>/fixtures.env.yaml is
  rendered with envsubst before it is applied, restricted to the variable names
  a chart declares in REQUIRED_ENV. A missing or empty declared variable fails
  the run loudly and names the variable - it never skips the chart.
- The install-test job loads the key from 1Password Connect for freesailarr
  only, following the pattern publish-helm-chart.yml documents: values via
  steps.<id>.outputs.*, mapped into the step's own env, quoted, with ":?"
  guards that name the missing op:// field before a cluster is created.
- Fixtures for freesailarr: three media claims, the gluetun secret template
  with variable names only, firewallOutboundSubnets so the kill switch does not
  block cluster DNS, and INSTALL_TIMEOUT=900 for nine containers.

freesailarr/Chart.yaml goes 3.0.0+up1.0.0 -> 3.0.1+up1.0.0. That bump is
deliberately empty of content: the install-test matrix follows changed chart
directories, and without it this PR could not run the test it adds.

ci/freesailarr/settings.env

@@ -0,0 +1,10 @@
+# Nine containers in one pod, several GB of images to pull, and the app
+# containers only start once gluetun has completed its Wireguard handshake -
+# each of them then runs its own startup probe (150s budget, 300s for seerr's
+# first-boot migrations). The default of 300s is not enough for that.
+INSTALL_TIMEOUT=900
+
+# The gluetun credentials for ci/freesailarr/fixtures.env.yaml. Missing or empty
+# values fail the install-test loudly instead of skipping it - see
+# ci/run-install-test.sh.
+REQUIRED_ENV="FREESAILARR_WG_KEY FREESAILARR_WG_ADDRESSES"