fix: refactor 5 additional aliased output.args mutations + strengthen audit test

Address Oracle review feedback: refactor 4 aliased mutations via argsObject
in plugin/tool-execute-before.ts and 1 via toolOutput in atlas/tool-execute-before.ts.
Strengthen audit test regex to catch Output.args mutations regardless of the
variable name prefix (toolOutput, argsObject aliases).

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/atlas/tool-execute-before.ts

@@ -1,4 +1,5 @@
 import { log } from "../../shared/logger"
+import { replaceToolArgs } from "../../shared/replace-tool-args"
 import { SYSTEM_DIRECTIVE_PREFIX } from "../../shared/system-directive"
 import { isCallerOrchestrator } from "../../shared/session-utils"
 import type { PluginInput } from "@opencode-ai/plugin"
@@ -179,7 +180,7 @@ export function createToolExecuteBeforeHandler(input: {
 
       const prompt = toolOutput.args.prompt as string | undefined
       if (prompt && !prompt.includes(SYSTEM_DIRECTIVE_PREFIX)) {
-        toolOutput.args.prompt = `<system-reminder>${SINGLE_TASK_DIRECTIVE}</system-reminder>\n` + prompt
+        replaceToolArgs(toolOutput, { prompt: `<system-reminder>${SINGLE_TASK_DIRECTIVE}</system-reminder>\n` + prompt })
         log(`[${HOOK_NAME}] Injected single-task directive to task`, {
           sessionID: toolInput.sessionID,
         })