[ci skip] add auto-generated tiers.tf, planning docs, and helm chart cache

- tiers.tf: Terragrunt-generated tier locals for all standalone stacks
- .planning/: resource audit research and plans
- docs/plans/: cluster hardening design doc
- redis-25.3.2.tgz: Bitnami Redis Helm chart cache

stacks/shadowsocks/tiers.tf

@@ -0,0 +1,10 @@
+# Generated by Terragrunt. Sig: nIlQXj57tbuaRZEa
+locals {
+  tiers = {
+    core    = "0-core"
+    cluster = "1-cluster"
+    gpu     = "2-gpu"
+    edge    = "3-edge"
+    aux     = "4-aux"
+  }
+}