feat: add branchSummary.skipPrompt setting to skip summarization prompt (#1792)

When enabled, /tree navigation skips the 'Summarize branch?' prompt and
defaults to no summary, reducing friction for users who never want branch
summaries.

Closes #1791

packages/coding-agent/src/core/settings-manager.ts

@@ -12,6 +12,7 @@ export interface CompactionSettings {
 
 export interface BranchSummarySettings {
 	reserveTokens?: number; // default: 16384 (tokens reserved for prompt + LLM response)
+	skipPrompt?: boolean; // default: false - when true, skips "Summarize branch?" prompt and defaults to no summary
 }
 
 export interface RetrySettings {
@@ -607,12 +608,17 @@ export class SettingsManager {
 		};
 	}
 
-	getBranchSummarySettings(): { reserveTokens: number } {
+	getBranchSummarySettings(): { reserveTokens: number; skipPrompt: boolean } {
 		return {
 			reserveTokens: this.settings.branchSummary?.reserveTokens ?? 16384,
+			skipPrompt: this.settings.branchSummary?.skipPrompt ?? false,
 		};
 	}
 
+	getBranchSummarySkipPrompt(): boolean {
+		return this.settings.branchSummary?.skipPrompt ?? false;
+	}
+
 	getRetryEnabled(): boolean {
 		return this.settings.retry?.enabled ?? true;
 	}