satisfactory: server.storage stays the documented exception (#39)

Walks back the one part of the previous commit that changed rendered output:
storage was pulled into the server fallback, so an erased size fell back to
20Gi instead of rendering a PVC without one.

values.schema.json had documented the opposite decision - "an erased value
yields an invalid PVC rather than a silently degraded workload" - and that is
someone's reasoned trade, not collateral of the nil-pointer bug next to it.
Overturning it inside a patch would have made this the only release where
valid values render differently, and it would have settled an open design
question in a PR nobody opened for that. It goes to #39 instead.

So storage is out of the defaults again and the schema note is restored
verbatim, extended only by where the exception is argued. values.yaml marks
it as the one key of the block that is deliberately not null-safe. The
README rule that had leaned on this example now says the thing that actually
holds: an exception is fine, an unmarked one is not.

Everything else stands - dev and server null-safe, the single-key findings on
the ports, formatNumber against exponential notation, 7.0.1.

Re-measured after the walk-back: rendered output against the chart defaults
and against a full override set is byte-identical to 7.0.0, NOTES.txt
included, and "--set server=null" now renders exactly the sizeless PVC that
"--set server.storage=null" rendered on 7.0.0.

satisfactory/values.yaml

@@ -32,18 +32,22 @@ game:
   enableSeasonalEvents: false
 
 # Erasing this block, or any single key in it, falls back to the defaults below
-# (Gitea issue #16). Before 7.0.1 "server: null" aborted the render and a single
-# erased key was worse: a nulled gamePort rendered an empty port number into the
-# Service and the StatefulSet, and a nulled storage a PVC without a size — both
-# rejected by the API server at apply time, not by the render.
+# (Gitea issue #16) — with the documented exception of storage, see there.
+# Before 7.0.1 "server: null" aborted the render, and a single erased key was
+# the quieter half: a nulled gamePort rendered an empty port number into the
+# Service and the StatefulSet, rejected by the API server at apply time and by
+# nothing before it.
 server:
   # Replica count for this workload; 0 is allowed and scales it down.
   # The chart-global scaleDown flag takes precedence.
   replicas: 1
   gamePort: 30777
   messagingPort: 30888
-  # The size of the data PVC. An erased value falls back to this default; up to
-  # 7.0.0 it rendered a PVC asking for no size at all.
+  # The size of the data PVC, and the ONE key of this block that is NOT
+  # null-safe — deliberately, not by oversight. An erased storage (including
+  # "server: null") renders a PVC without a size, which fails at apply time
+  # instead of quietly sizing the volume from the chart. Whether that is still
+  # the right trade is negotiated in Gitea issue #39, not here.
   storage: 20Gi
   resources:
     # Limits are optional: memory and ephemeral-storage limits default to