Add xhigh thinking level for OpenAI codex-max models

- Add 'xhigh' to ThinkingLevel type in ai and agent packages
- Map xhigh to reasoning_effort: 'max' for OpenAI providers
- Add thinkingXhigh color token to theme schema and built-in themes
- Show xhigh option only when using codex-max models
- Update CHANGELOG for both ai and coding-agent packages

closes #143

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

@@ -12,12 +12,13 @@ export interface Settings {
 	lastChangelogVersion?: string;
 	defaultProvider?: string;
 	defaultModel?: string;
-	defaultThinkingLevel?: "off" | "minimal" | "low" | "medium" | "high";
+	defaultThinkingLevel?: "off" | "minimal" | "low" | "medium" | "high" | "xhigh";
 	queueMode?: "all" | "one-at-a-time";
 	theme?: string;
 	compaction?: CompactionSettings;
 	hideThinkingBlock?: boolean;
 	shellPath?: string; // Custom shell path (e.g., for Cygwin users on Windows)
+	collapseChangelog?: boolean; // Show condensed changelog after update (use /changelog for full)
 }
 
 export class SettingsManager {
@@ -109,11 +110,11 @@ export class SettingsManager {
 		this.save();
 	}
 
-	getDefaultThinkingLevel(): "off" | "minimal" | "low" | "medium" | "high" | undefined {
+	getDefaultThinkingLevel(): "off" | "minimal" | "low" | "medium" | "high" | "xhigh" | undefined {
 		return this.settings.defaultThinkingLevel;
 	}
 
-	setDefaultThinkingLevel(level: "off" | "minimal" | "low" | "medium" | "high"): void {
+	setDefaultThinkingLevel(level: "off" | "minimal" | "low" | "medium" | "high" | "xhigh"): void {
 		this.settings.defaultThinkingLevel = level;
 		this.save();
 	}
@@ -163,4 +164,13 @@ export class SettingsManager {
 		this.settings.shellPath = path;
 		this.save();
 	}
+
+	getCollapseChangelog(): boolean {
+		return this.settings.collapseChangelog ?? false;
+	}
+
+	setCollapseChangelog(collapse: boolean): void {
+		this.settings.collapseChangelog = collapse;
+		this.save();
+	}
 }