ci: hold every scalar that must be a string, and the required podAffinity

The test Gitea #11 asked for ("whoever fixes this ships a test case that would
have caught it"), plus the guard for the fix #101 introduces.

ci/run-yaml-scalar-render-test.sh renders every chart with the fixtures the
install-test already uses and asserts three properties Kubernetes itself
requires, so no per-chart expectations are needed: a CronJob schedule is a
non-empty string, every env[].value of every container and initContainer is a
string, and every label and annotation value is a string. The first catches the
loud failure - the render aborting with a YAML error that names the template
and not the value - and the other two catch the quiet one, where the render
succeeds and the API server rejects the object at apply time.

WHY A NEW JOB AND NOT THE INSTALL-TEST. The object that carried the defect is
rendered by no fixture at all: paperless-ngx' consume CronJob sits behind
smbConnection.enabled, false in the chart defaults and false in its install-test
fixture, since the CI cluster has no SMB CSI driver. Nothing in this repository
ever produced it. So the overlays under ci/yaml-scalar/ are the test, not the
scaffolding: they switch such objects on AND feed them hostile values, and the
script fails when an overlay stops reaching its object or when the run asserted
nothing at all.

The fail path was exercised in all three shapes against a throwaway copy of the
chart as it stands on main, not reasoned about: the bare schedule aborted with
"yaml: line 6: did not find expected alphabetic or numeric character"; with only
the schedule quoted, the star-valued env entry aborted on the StatefulSet
instead; and with only the bool-looking value left - a render that succeeds -
the type assertion named the variable, the container and the API server's
message. Green repo-wide otherwise: 30 charts, 408 scalars, 0 failed.

ci/run-selector-match-test.sh additionally holds every
requiredDuringSchedulingIgnoredDuringExecution podAffinity term against all pod
templates of the same render (Gitea #101). That case is not the gap the script's
header describes: a preference that cannot be met is dropped and an
anti-affinity over zero pods is satisfied, but a REQUIRED term matching no pod
can never be satisfied and the pod stays Pending for good. paperless-ngx' mover
selects a label written in another template, which is exactly the copy this test
holds - renaming it would leave both templates rendering perfectly while the
mover silently stopped moving. Exercised by doing that rename in a throwaway
copy: one FAIL naming the selector, the pod templates it missed and the labels
actually present.

Six charts still render their env block bare (matrix-synapse, minecraft-router,
minecraft-server, rallly, satisfactory, teamspeak-server). They are green only
because no fixture of theirs sets a hostile value; README now says so instead of
repeating template-chart's claim that every chart quotes.

Part of #11
Part of #101

ci/yaml-scalar/paperless-ngx.yaml

@@ -0,0 +1,53 @@
+# YAML-scalar overlay for paperless-ngx (Gitea #11).
+#
+# THIS FILE IS THE TEST CASE the issue asked for, and its first job is to make
+# an object exist at all. templates/paperless-consume.cronjob.yaml sits behind
+# smbConnection.enabled, which is false in the chart defaults and false in
+# ci/paperless-ngx/test-values.yaml - deliberately, because the install-test has
+# no SMB CSI driver. So before this overlay NOTHING in the repository rendered
+# that CronJob: not lint, not the render tests, not the install-test. That is
+# the whole reason an unquoted schedule survived in a shipped chart, and it is
+# why the fix comes with a render test rather than with a fixture change.
+#
+# The values below are hostile on purpose. Against the chart before 13.0.0 this
+# overlay does not produce a finding - it produces an aborted render, which this
+# test reports as the finding it is:
+#
+#   Error: YAML parse error on paperless-ngx/templates/paperless-consume.cronjob.yaml:
+#   error converting YAML to JSON: yaml: line 6: did not find expected
+#   alphabetic or numeric character
+smbConnection:
+  enabled: true
+  server: "//smb.ci.local/scans"
+  # A schedule beginning with "*" - the commonest cron notation there is, and
+  # the one that YAML reads as an alias indicator. Written here as a quoted
+  # string, which is exactly how an operator would write it and exactly what
+  # does NOT help: Helm passes the content through, and without | quote in the
+  # template the star stands bare in the manifest again.
+  cronJob: "*/15 * * * *"
+
+secrets:
+  # The CronJob's SMB volume has a required() secret ref behind it; the
+  # PersistentVolume names it as nodeStageSecretRef. Nothing is mounted in a
+  # render, so no fixture Secret is needed - only a value that satisfies the
+  # required().
+  smbConnectionSecretRef: op://ci/paperless-smb
+
+paperless:
+  # The silent half of the genus, on the chart's additive env block: both of
+  # these are STRINGS in this file and both are schema-valid, and before 13.0.0
+  # the first one aborted the render while the second arrived in the manifest as
+  # a YAML bool - which the API server rejects at apply time with "cannot
+  # unmarshal bool into Go struct field EnvVar.value of type string", so the
+  # render test is the only place it can be caught cheaply.
+  env:
+    - name: PAPERLESS_STAR_VALUE
+      value: "*never-interpreted*"
+    - name: PAPERLESS_BOOLEAN_LOOKING_VALUE
+      value: "true"
+    # The variable the whole env block was asked for (Gitea #112): the log off
+    # the NFS-backed RWX data volume and onto the /tmp emptyDir this pod already
+    # mounts. Harmless in a render, and it keeps the worked example honest by
+    # being the one an operator will actually copy.
+    - name: PAPERLESS_LOGGING_DIR
+      value: "/tmp/paperless-log"