🤖 feat: add guard-anchored file_edit_insert tool (#579)

## Summary
- implement file_edit_insert with optional before/after substring guards
plus line_offset fallback, including new runtime tool + unit coverage
- wire the tool through type defs, tokenizer accounting, redaction, and
UI rendering so agents can call it safely
- refresh tool policy + runtime IPC tests to favor file_edit_insert and
ensure redactors/tests understand the new tool

## Testing
- make typecheck
- make test

_Generated with `mux`_

---------

Co-authored-by: root <root@ovh-1.tailc2a514.ts.net>

Author: ammar-agent

src/components/Messages/ToolMessage.tsx

@@ -13,9 +13,9 @@ import type {
   BashToolResult,
   FileReadToolArgs,
   FileReadToolResult,
+  FileEditReplaceStringToolArgs,
   FileEditInsertToolArgs,
   FileEditInsertToolResult,
-  FileEditReplaceStringToolArgs,
   FileEditReplaceStringToolResult,
   FileEditReplaceLinesToolArgs,
   FileEditReplaceLinesToolResult,
@@ -121,26 +121,26 @@ export const ToolMessage: React.FC<ToolMessageProps> = ({ message, className, wo
     );
   }
 
-  if (isFileEditReplaceLinesTool(message.toolName, message.args)) {
+  if (isFileEditInsertTool(message.toolName, message.args)) {
     return (
       <div className={className}>
         <FileEditToolCall
-          toolName="file_edit_replace_lines"
+          toolName="file_edit_insert"
           args={message.args}
-          result={message.result as FileEditReplaceLinesToolResult | undefined}
+          result={message.result as FileEditInsertToolResult | undefined}
           status={message.status}
         />
       </div>
     );
   }
 
-  if (isFileEditInsertTool(message.toolName, message.args)) {
+  if (isFileEditReplaceLinesTool(message.toolName, message.args)) {
     return (
       <div className={className}>
         <FileEditToolCall
-          toolName="file_edit_insert"
+          toolName="file_edit_replace_lines"
           args={message.args}
-          result={message.result as FileEditInsertToolResult | undefined}
+          result={message.result as FileEditReplaceLinesToolResult | undefined}
           status={message.status}
         />
       </div>