Add configurable stratum port (default 3333)

Exposes stratum-port in the StartOS config UI so users running
simpleproxy or another TCP forwarder can point Kamado at a
non-default port. Entrypoint substitutes the value into
ckpool.conf serverurl.

Also pins placeholder KAMADO_SHA in the Dockerfile — swap to a
real pushed commit before the first build.

scripts/procedures/getConfig.ts

@@ -81,6 +81,16 @@ export const getConfig: T.ExpectedExports.getConfig = compat.getConfig({
     "masked": false,
     "copyable": false,
   },
+  "stratum-port": {
+    "type": "number",
+    "name": "Stratum Port",
+    "description":
+      "TCP port the stratum server listens on inside the container. Defaults to 3333. Change this if you are running simpleproxy (or another TCP forwarder) and want Kamado to listen on a different port — useful when another service on the same host already uses 3333.",
+    "nullable": false,
+    "default": 3333,
+    "range": "[1,65535]",
+    "integral": true,
+  },
   "startdiff": {
     "type": "number",
     "name": "Starting Difficulty",