refactor: remove heuristic parsing, use pure type-based tool rendering

- Remove all heuristic parsing code from message.tsx (hasCommandDetails,
  commandSection, editSections, readSections, hasStructuredContent, etc.)
- Replace with simple raw JSON fallback for tools without structured results
- Fix server-side support for Claude SDK's old_string/new_string params
  (in addition to old_str/new_str)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/server/src/server/agent/providers/claude-agent.ts

@@ -1122,12 +1122,15 @@ class ClaudeAgentSession implements AgentSession {
       normalizedTool === "apply_diff"
     ) {
       if (input && typeof input.file_path === "string") {
+        // Support both old_str/new_str and old_string/new_string parameter names
+        const oldContent = typeof input.old_str === "string" ? input.old_str : typeof input.old_string === "string" ? input.old_string : undefined;
+        const newContent = typeof input.new_str === "string" ? input.new_str : typeof input.new_string === "string" ? input.new_string : undefined;
         return {
           type: "file_edit",
           filePath: input.file_path,
           diff: typeof input.patch === "string" ? input.patch : typeof input.diff === "string" ? input.diff : undefined,
-          oldContent: typeof input.old_str === "string" ? input.old_str : undefined,
-          newContent: typeof input.new_str === "string" ? input.new_str : undefined,
+          oldContent,
+          newContent,
         };
       }
     }