Convert all schemas to flat format with inline required/secret

All schemas (parameters, output, output_schema, conf_schema) now use the
StackStorm-style flat format expected by Attune:
  { param_name: { type, description, required, secret, ... } }

Instead of the standard JSON Schema format:
  { type: object, properties: { ... }, required: [...] }

Also fix rule template syntax: trigger.payload.* -> event.payload.*

pack.yaml

@@ -11,14 +11,12 @@ email: "support@attune.io"
 system: false
 enabled: true
 
-# Pack configuration schema
+# Pack configuration schema (flat format with inline required/secret)
 conf_schema:
-  type: object
-  properties:
-    counter_key_prefix:
-      type: string
-      description: "Prefix for counter keys in the keystore"
-      default: "python_example.counter"
+  counter_key_prefix:
+    type: string
+    description: "Prefix for counter keys in the keystore"
+    default: "python_example.counter"
 
 # Default pack configuration
 config: