feat: support require_plan_approval in template config

Templates can now set "require_plan_approval": true in template.json
to require user approval after plan generation before execution begins.
On rejection, the LLM re-enters the planning loop with user feedback.

src/template.rs

@@ -12,6 +12,10 @@ pub struct TemplateInfo {
     pub name: String,
     pub description: String,
     pub match_hint: String,
+    /// If true, the agent will wait for user approval after update_plan
+    /// before entering the execution phase.
+    #[serde(default)]
+    pub require_plan_approval: bool,
 }
 
 #[allow(dead_code)]
@@ -21,6 +25,7 @@ pub struct LoadedTemplate {
     pub instructions: String,
     pub external_tools: ExternalToolManager,
     pub kb_files: Vec<(String, String)>,
+    pub require_plan_approval: bool,
 }
 
 #[derive(Debug, Clone, serde::Serialize)]
@@ -590,12 +595,14 @@ impl LoadedTemplate {
                 name: template_id.to_string(),
                 description: String::new(),
                 match_hint: String::new(),
+                require_plan_approval: false,
             })
         } else {
             TemplateInfo {
                 name: template_id.to_string(),
                 description: String::new(),
                 match_hint: String::new(),
+                require_plan_approval: false,
             }
         };
 
@@ -610,12 +617,15 @@ impl LoadedTemplate {
         let kb_files = scan_kb_files(&kb_dir).await;
         tracing::info!("Template '{}': {} KB files", template_id, kb_files.len());
 
+        let require_plan_approval = info.require_plan_approval;
+
         Ok(Self {
             id: template_id.to_string(),
             info,
             instructions,
             external_tools,
             kb_files,
+            require_plan_approval,
         })
     }