feat: AI 修复链路扩展 + 修复预览两步确认 + 自定义规则/AI 审查条目支持 AI 修复

- AI 修复：无原生 fix 的 linter 条目走 AI 修复（aiFixEngine/fixPrompt，AI 重检收敛），自定义规则与 AI 审查条目新增 AI 修复按钮（customFixEngine），自定义规则条目展开显示 AI 建议（suggestion 字段）

- 修复预览：面板触发修复先用内置 diff 预览，面板内「应用/取消」两步确认后才写入（fixPreview/fixPending，单条与分 tab 批量均支持）

- 修复面板交互：linter/custom/ai 分 tab「全部修复」、已修复+撤销、pending 按钮状态同步

- bug 修复：修复按钮失败后卡 ⏳ 不恢复；custom/ai 修复不稳定（空修复重试、AI 重检收敛判定放宽、降级接受最后一次有效修复）

- 移除 AI codeDiff 展示块

src/ai/engine.ts

@@ -105,7 +105,8 @@ function buildCustomRuleSystemPrompt(): string {
     return `あなたはコードルールレビュアーです。以下のカスタムルールに違反しているかどうかのみを評価してください。
 意味を理解し、テキストの一致ではなく判断してください。
 JSONのみを出力、形式：
-{ "customRuleResults": [{ "ruleId": "ルールID", "line": 行番号, "severity": "error|warning|info", "message": "違反の説明" }] }
+{ "customRuleResults": [{ "ruleId": "ルールID", "line": 行番号, "severity": "error|warning|info", "message": "違反の説明", "suggestion": "具体的な修正提案" }] }
+"suggestion" は実行可能な修正提案を必ず含めてください。
 ルールに違反していない場合は空の配列を返してください。
 
 出力言語：ja`;
@@ -114,7 +115,8 @@ JSONのみを出力、形式：
     return `You are a code rule reviewer. Only evaluate whether the following custom rules are violated.
 Understand semantics, not text matching.
 Output JSON only, format:
-{ "customRuleResults": [{ "ruleId": "rule id", "line": line number, "severity": "error|warning|info", "message": "violation description" }] }
+{ "customRuleResults": [{ "ruleId": "rule id", "line": line number, "severity": "error|warning|info", "message": "violation description", "suggestion": "concrete fix suggestion" }] }
+Always include a concrete actionable "suggestion" for each violation.
 If no rules are violated, return an empty array.
 
 Output language: en`;
@@ -122,7 +124,8 @@ Output language: en`;
   return `你是代码规则审查员，只评估以下自定义规则是否被违反。
 理解语义而非文本匹配。
 仅输出 JSON，格式：
-{ "customRuleResults": [{ "ruleId": "规则ID", "line": 行号, "severity": "error|warning|info", "message": "触发描述" }] }
+{ "customRuleResults": [{ "ruleId": "规则ID", "line": 行号, "severity": "error|warning|info", "message": "触发描述", "suggestion": "具体的修复建议" }] }
+每条违规都必须给出可执行的 "suggestion" 修复建议。
 如果没有违反任何规则，返回空数组。
 
 输出语言：zh-CN`;
@@ -146,8 +149,8 @@ translatedDiagnosticsの要件：
 JSONのみを出力。文字列内の二重引用符は \\" でエスケープしてください。
 形式：
 {
-  "translatedDiagnostics": [{ "originalRuleId": "元のID", "translatedMessage": "翻訳メッセージ", "translatedSuggestion": "提案", "codeDiff": "任意" }],
-  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "タイトル", "description": "説明", "suggestion": "提案", "codeDiff": "任意", "line": 行番号 }]
+  "translatedDiagnostics": [{ "originalRuleId": "元のID", "translatedMessage": "翻訳メッセージ", "translatedSuggestion": "提案" }],
+  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "タイトル", "description": "説明", "suggestion": "提案", "line": 行番号 }]
 }
 
 出力言語：ja`;
@@ -168,8 +171,8 @@ translatedDiagnostics requirements:
 Output JSON only. Double quotes in strings must be escaped with \\".
 Format:
 {
-  "translatedDiagnostics": [{ "originalRuleId": "original id", "translatedMessage": "translated message", "translatedSuggestion": "suggestion", "codeDiff": "optional" }],
-  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "title", "description": "description", "suggestion": "suggestion", "codeDiff": "optional", "line": line number }]
+  "translatedDiagnostics": [{ "originalRuleId": "original id", "translatedMessage": "translated message", "translatedSuggestion": "suggestion" }],
+  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "title", "description": "description", "suggestion": "suggestion", "line": line number }]
 }
 
 Output language: en`;
@@ -189,8 +192,8 @@ translatedDiagnostics 要求：
 仅输出 JSON，字符串中的双引号必须用 \\" 转义。
 格式：
 {
-  "translatedDiagnostics": [{ "originalRuleId": "原始ID", "translatedMessage": "翻译", "translatedSuggestion": "建议", "codeDiff": "可选" }],
-  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "标题", "description": "描述", "suggestion": "建议", "codeDiff": "可选", "line": 行号 }]
+  "translatedDiagnostics": [{ "originalRuleId": "原始ID", "translatedMessage": "翻译", "translatedSuggestion": "建议" }],
+  "findings": [{ "ruleId": "kebab-case", "severity": "error|warning|info", "category": "bug|performance|security|style|design", "title": "标题", "description": "描述", "suggestion": "建议", "line": 行号 }]
 }
 
 输出语言：zh-CN`;
@@ -426,7 +429,8 @@ Report violations in "customRuleResults".\n\n`
       "ruleId": "original rule id",
       "line": line_number,
       "severity": "error|warning|info",
-      "message": "violation description"
+      "message": "violation description",
+      "suggestion": "concrete fix suggestion"
     }
   ],\n`
     : '';
@@ -463,7 +467,6 @@ ${ruleOutput}  "findings": [
       "title": "issue title",
       "description": "detailed description",
       "suggestion": "fix suggestion",
-      "codeDiff": "optional fix diff",
       "line": line_number,
       "path": "trigger path description, e.g. if(order==null) -> NPE on .getId()"
     }
@@ -487,7 +490,8 @@ function buildMethodSystemPromptZh(hasRules: boolean): string {
       "ruleId": "原始规则 ID",
       "line": 行号,
       "severity": "error|warning|info",
-      "message": "违规描述"
+      "message": "违规描述",
+      "suggestion": "具体的修复建议"
     }
   ],\n`
     : '';
@@ -524,7 +528,6 @@ ${ruleOutput}  "findings": [
       "title": "问题标题",
       "description": "详细描述",
       "suggestion": "修复建议",
-      "codeDiff": "可选的修复 diff",
       "line": 行号,
       "path": "触发路径描述，如 if(order==null) -> NPE on .getId()"
     }
@@ -548,7 +551,8 @@ function buildMethodSystemPromptJa(hasRules: boolean): string {
       "ruleId": "元のルールID",
       "line": 行番号,
       "severity": "error|warning|info",
-      "message": "違反の説明"
+      "message": "違反の説明",
+      "suggestion": "具体的な修正提案"
     }
   ],\n`
     : '';
@@ -585,7 +589,6 @@ ${ruleOutput}  "findings": [
       "title": "問題のタイトル",
       "description": "詳細な説明",
       "suggestion": "修正提案",
-      "codeDiff": "オプションの修正diff",
       "line": 行番号,
       "path": "トリガーパス説明、例: if(order==null) -> .getId() で NPE"
     }