Remove manual polish scenario UI; rely on auto AppContext only

- Hide AppContext chip and remove manual override from keyboard
- Remove polish scenario picker and custom system prompt from settings
- Remove scenario section from onboarding
- Translation prompt uses auto-detected AppContext instead of polish scenario
- Delete ScenarioPrompt, ScenarioStyleDirective, PolishScenario, and related views

Co-authored-by: Rocky <hkgood@users.noreply.github.com>

OSGKeyboardShared/Services/TranslationPrompt.swift

@@ -3,75 +3,57 @@
 //
 // Builds the system prompt the LLM sees when the user has the
 // translation toggle on. Re-uses the same per-provider "primary
-// language" split the polish prompt uses (`AppGroupStore.defaultSystemPrompt`)
-// so Chinese-native LLMs (DeepSeek, Qwen, GLM, Moonshot) get a Chinese
-// prompt and English-native LLMs (OpenAI) get an English one — the LLM
-// is most reliable when the instructions are written in its strongest
-// language.
+// language" split as `PolishingService.buildPrompt` so Chinese-native
+// LLMs get a Chinese prompt and English-native LLMs get an English one.
 //
 // The "translate AND polish" blend is intentional: ASR transcripts are
-// noisy (homophone errors, broken segmentation, dropped particles), so
-// the prompt asks the model to clean the noise while translating.
-// Scenario output format (`ScenarioStyleDirective`) is appended so
-// translate-and-polish honours the user's polish scenario choice.
+// noisy, so the prompt asks the model to clean the noise while translating.
+// Style follows the auto-detected `AppContext` (same as the polish path).
 
 import Foundation
 
 public enum TranslationPrompt {
 
     /// Build the translate-and-polish system prompt.
-    ///
-    /// - Parameters:
-    ///   - target: target language entry resolved via `TranslationLanguageCatalog`.
-    ///   - providerId: provider preset id (e.g. `"deepseek"`, `"openai"`);
-    ///     drives the language the prompt is written in.
-    ///   - scenarioId: active polish scenario; format rules are shared
-    ///     with the polish-only path via `ScenarioStyleDirective`.
-    ///   - uiLanguage: host-app UI language (platform label variants).
     public static func make(
         target: TranslationLanguage,
         providerId: String,
-        scenarioId: String = PolishScenarioCatalog.defaultId,
-        uiLanguage: AppUILanguage? = nil
+        appContext: AppContext = .unknown
     ) -> String {
         let isChineseNative = ["zhipu", "moonshot", "qwen", "deepseek"].contains(providerId)
-        let directive = ScenarioStyleDirective.make(
-            scenarioId: scenarioId,
-            providerId: providerId,
-            uiLanguage: uiLanguage
-        )
+        let contextGuideline = appContext.polishGuideline
         return isChineseNative
-            ? chinesePrompt(target: target, directive: directive)
-            : englishPrompt(target: target, directive: directive)
+            ? chinesePrompt(target: target, contextGuideline: contextGuideline)
+            : englishPrompt(target: target, contextGuideline: contextGuideline)
     }
 
     // MARK: - Chinese prompt (for DeepSeek / Qwen / GLM / Moonshot)
 
-    private static func chinesePrompt(target: TranslationLanguage, directive: String) -> String {
+    private static func chinesePrompt(target: TranslationLanguage, contextGuideline: String) -> String {
         """
         你是一位语音输入翻译与润色助手。用户用 ASR 转写了一段可能含噪声的口述:
         1) 先识别原话的主要语言(若不确定则按用户给定的方向处理);
         2) 将内容翻译为「\(target.promptLanguageName)」,保留原意,不增删事实、不臆测;
         3) 顺带修复 ASR 噪声(同音错字、漏字、断句错乱),让译文读起来自然;
-        4) 简洁;若下方场景未要求列表/分段,不超过原文 1.5 倍;去掉无意义的口头禅(嗯、啊、那个);
-        5) 若场景格式要求列表或分段,允许按格式组织译文;总长度不超过原长 2 倍;
-        6) 只输出译文正文,不要解释、不要加引号、不要前缀"以下是翻译"。
-        \(directive)
+        4) 简洁;不超过原文 1.5 倍;去掉无意义的口头禅(嗯、啊、那个);
+        5) 只输出译文正文,不要解释、不要加引号、不要前缀"以下是翻译"。
+
+        当前输入场景：\(contextGuideline)
         """
     }
 
     // MARK: - English prompt (for OpenAI / OpenAI-compatible non-Chinese)
 
-    private static func englishPrompt(target: TranslationLanguage, directive: String) -> String {
+    private static func englishPrompt(target: TranslationLanguage, contextGuideline: String) -> String {
         """
         You are a voice-input translation and polishing assistant. The user has spoken informally and the transcript may contain ASR noise:
         1) Identify the input language; if unclear, assume the user wants translation INTO \(target.promptLanguageName);
         2) Translate the content INTO \(target.promptLanguageName), preserving meaning; do not invent facts or omit content;
         3) Fix ASR noise (homophone errors, missing characters, broken segmentation) so the translation reads naturally;
-        4) Stay concise; if the scenario below does not require lists/sections, do not exceed 1.5x the spoken length; drop filler words (um, uh, like);
-        5) If the scenario requires bullets or paragraph breaks, use that layout in the translation; total length may be up to 2x when listing;
-        6) Output ONLY the translation. No quotes, no preamble, no explanation.
-        \(directive)
+        4) Stay concise; do not exceed 1.5x the spoken length; drop filler words (um, uh, like);
+        5) Output ONLY the translation. No quotes, no preamble, no explanation.
+
+        Current input context: \(contextGuideline)
         """
     }
 }