Simplify agent mode and re-add additional_permissions input

- Agent mode now only triggers when explicit prompt is provided
- Removed automatic triggering for workflow_dispatch/schedule without prompt
- Re-added additional_permissions input for requesting GitHub permissions
- Fixed TypeScript types for mock context helpers to properly handle partial inputs
- Updated documentation to reflect simplified mode behavior

test/mockContext.ts

@@ -27,8 +27,12 @@ const defaultRepository = {
   full_name: "test-owner/test-repo",
 };
 
+type MockContextOverrides = Omit<Partial<ParsedGitHubContext>, 'inputs'> & {
+  inputs?: Partial<ParsedGitHubContext['inputs']>;
+};
+
 export const createMockContext = (
-  overrides: Partial<ParsedGitHubContext> = {},
+  overrides: MockContextOverrides = {},
 ): ParsedGitHubContext => {
   const baseContext: ParsedGitHubContext = {
     runId: "1234567890",
@@ -42,15 +46,19 @@ export const createMockContext = (
     inputs: defaultInputs,
   };
 
-  if (overrides.inputs) {
-    overrides.inputs = { ...defaultInputs, ...overrides.inputs };
-  }
+  const mergedInputs = overrides.inputs 
+    ? { ...defaultInputs, ...overrides.inputs }
+    : defaultInputs;
 
-  return { ...baseContext, ...overrides };
+  return { ...baseContext, ...overrides, inputs: mergedInputs };
+};
+
+type MockAutomationOverrides = Omit<Partial<AutomationContext>, 'inputs'> & {
+  inputs?: Partial<AutomationContext['inputs']>;
 };
 
 export const createMockAutomationContext = (
-  overrides: Partial<AutomationContext> = {},
+  overrides: MockAutomationOverrides = {},
 ): AutomationContext => {
   const baseContext: AutomationContext = {
     runId: "1234567890",
@@ -62,7 +70,11 @@ export const createMockAutomationContext = (
     inputs: defaultInputs,
   };
 
-  return { ...baseContext, ...overrides };
+  const mergedInputs = overrides.inputs 
+    ? { ...defaultInputs, ...overrides.inputs }
+    : defaultInputs;
+
+  return { ...baseContext, ...overrides, inputs: mergedInputs };
 };
 
 export const mockIssueOpenedContext: ParsedGitHubContext = {