Add explicit flush to append_entry and strengthen commit ordering docs

Add file.flush() call in append_entry() to ensure planner history
entries are written to disk before git commits execute. While the
file handle drop should flush, explicit flush simplifies reasoning
about the ordering invariant.

Extend code comments in stage_and_commit() to document that the
write_git_commit-before-git::commit ordering has regressed multiple
times and must be preserved in any refactoring.

Requirements: completed_requirements_2025-12-11_10-05-08.md

crates/g3-planner/src/llm.rs

@@ -242,10 +242,10 @@ impl g3_core::ui_writer::UiWriter for PlannerUiWriter {
         // Format args for display (first 50 chars, must be safe char boundary)
         let args_display = if let Some(args) = tool_args {
             let args_str = serde_json::to_string(args).unwrap_or_else(|_| "{}".to_string());
-            if args_str.len() > 50 {
+            if args_str.len() > 100 {
                 // Use char_indices to safely truncate at char boundary
                 let truncate_idx = args_str.char_indices()
-                    .nth(50)
+                    .nth(100)
                     .map(|(idx, _)| idx)
                     .unwrap_or(args_str.len());
                 args_str[..truncate_idx].to_string()
@@ -257,7 +257,7 @@ impl g3_core::ui_writer::UiWriter for PlannerUiWriter {
         };
         
         // Print on EXACTLY one line using ui_writer.println
-        self.println(&format!("🔧 [{}] {}  {}", count, tool_name, args_display));
+        self.println(&format!("🔧 [{}] \x1b[38;5;240m{}  {}\x1b[39m", count, tool_name, args_display));
     }
     
     fn print_tool_arg(&self, _key: &str, _value: &str) {}
@@ -270,7 +270,9 @@ impl g3_core::ui_writer::UiWriter for PlannerUiWriter {
     fn print_agent_prompt(&self) {
         // No-op - don't add extra blank lines
     }
-    
+
+    // NOTE: this is a partial response, so don't print newlines. Ideally we'd accumulate the
+    // message and only then print it.
     fn print_agent_response(&self, content: &str) {
         // Display non-tool text messages from LLM without adding extra newlines
         let trimmed = content.trim_end();