refactor: remove redundant type casts in agent-session and browser tool

Three redundant 'as boolean' casts on settings.get() return values:
- agent-session.ts: settings.get('advisor.enabled') as boolean
- browser.ts: settings.get('browser.cmux') as boolean | undefined
- browser.ts: settings.get('browser.headless') as boolean

SettingValue<P> already resolves to boolean for these paths (they
have type: 'boolean' with a non-undefined default in the schema),
making the casts unnecessary.

Author: oldschoola

packages/coding-agent/src/session/agent-session.ts

@@ -1734,7 +1734,7 @@ export class AgentSession {
 			},
 		});
 
-		this.#advisorEnabled = this.settings.get("advisor.enabled") as boolean;
+		this.#advisorEnabled = this.settings.get("advisor.enabled");
 		if (this.#advisorEnabled) this.#buildAdvisorRuntime();
 
 		// Always subscribe to agent events for internal handling

packages/coding-agent/src/tools/browser.ts

@@ -81,12 +81,12 @@ function resolveBrowserKind(params: BrowserParams, session: ToolSession): Browse
 		return { kind: "spawned", path: exe };
 	}
 	const cmuxKind = resolveCmuxKind({
-		settingEnabled: session.settings.get("browser.cmux") as boolean | undefined,
+		settingEnabled: session.settings.get("browser.cmux"),
 	});
 	if (cmuxKind) {
 		return cmuxKind;
 	}
-	const headless = session.settings.get("browser.headless") as boolean;
+	const headless = session.settings.get("browser.headless");
 	return { kind: "headless", headless };
 }