fix(forgejo): raise the shared storage to 60Gi, the registry outgrew 20Gi

The container registry stores blobs on this volume. A single candle-vllm sm_70
image is 14GB, so a 20Gi volume cannot hold one. It filled, and every blob
upload failed:

  Package registry API internal error: 500 write
  /data/tmp/package-upload/<id>: no space left on device

The push client reports that as `received unexpected HTTP status: 500` after
retrying every layer, which reads like a network or auth fault. It is neither.

Applied live first (20Gi -> 40Gi -> 60Gi) and verified: /data now reports
58.9G total with 39.3G free, and the sm70 image pushed and verified by digest
sha256:8533d742dfe99c926f42cf99db33e057acb1aafc4b74b0ac22f697f4a45cba27.

This commit reconciles the chart with the live PVC, which is why the Application
currently reads OutOfSync.

NOTE FOR THE NEXT EXPANSION: Longhorn's admission webhook checks the PHYSICAL
free space of the disk holding each replica, not the thin volume size. A request
for 100Gi was rejected outright:

  disk ... does not have sufficient physical space for expansion:
  physical free space would drop below minimal:
  left=14596177920 < minimal=49931236556

60Gi fit on the same disk. Raise it in steps, and read the webhook message
rather than retrying the same number.

k8s/bootstrap/phase3-forgejo/forgejo-values.yaml

@@ -97,10 +97,25 @@ gitea:
       # USER and PASSWD injected via env vars below (GITEA__MAILER__USER, GITEA__MAILER__PASSWD)
 
 # Persistence (shared storage for repos)
+#
+# 60Gi, not the original 20Gi. The container registry stores its blobs here,
+# and a single candle-vllm sm_70 image is 14GB uncompressed. At 20Gi the volume
+# filled, and every blob upload failed with:
+#   Package registry API internal error: 500 write /data/tmp/package-upload/...:
+#   no space left on device
+# The push client surfaces that as a bare `received unexpected HTTP status: 500`
+# after retrying every layer, which looks like a network fault and is not one.
+#
+# Note for whoever expands this again: Longhorn's admission webhook checks the
+# PHYSICAL free space of the disk holding each replica, not the thin volume
+# size. A request for 100Gi was rejected while the disk had 23.5Gi free:
+#   disk ... does not have sufficient physical space for expansion:
+#   physical free space would drop below minimal: left=14596177920 < minimal=49931236556
+# 60Gi fit. Raise it in steps and watch the webhook message.
 persistence:
   enabled: true
   storageClass: longhorn
-  size: 20Gi
+  size: 60Gi
   accessModes:
     - ReadWriteOnce