Language-aware house style and a resizable chat split

House style now follows the app language: Chinese UI forces the new
bundled humanizer-zh skill into every run, English forces humanizer -
one variant per run, picked by preference with cross-language fallback
so an older catalogue never silently loses house style. Both variants
are protected from grant/revoke, list_skills labels each with its
language, the bundle guard requires both, and startup sync imports the
new skill into existing orgs on next launch. Covered by a unit test
that flips app_state.language and asserts which humanizer compiles.

The chat split is now adjustable: drag the conversation list's right
edge (200-480px, persisted in localStorage) and the composer textarea
grew a native vertical resize grip capped at 40vh.

src/main/services/agent-skill-tools.ts

@@ -29,7 +29,8 @@ export function listSkillsTool(deps: AgentToolDeps, ctx: AgentToolContext): stri
   const lines = skills.map((skill) => {
     const summary = skillSummary(skill.manifest_json);
     if (forced.has(skill.slug)) {
-      return `- ${skill.name} (${skill.slug})${summary}: house style — every agent carries it automatically`;
+      const language = skill.slug === "humanizer-zh" ? "Chinese" : "English";
+      return `- ${skill.name} (${skill.slug})${summary}: house style — carried automatically by every agent when the app language is ${language}`;
     }
     const holders = bindings
       .filter((binding) => binding.skill_id === skill.id)