feat(pricing): seed gpt-5.6 alias rows and 1.25x cache-write rates

- Add the bare gpt-5.6 row (official Sol alias) plus effort-suffix variants
  mirroring the gpt-5.5 accounting shape, priced at Sol rates
- The GPT-5.6 family charges cache writes at 1.25x the uncached input rate
  (new for OpenAI; earlier GPT models keep their correct zero): set
  6.25 / 3.125 / 1.25 for Sol / Terra / Luna across seed rows
- Repair earlier zero-value gpt-5.6 tier seeds in existing databases,
  matching only untouched rows so user-customized prices survive

src-tauri/src/database/schema.rs

@@ -1510,9 +1510,24 @@ impl Database {
                 "3.75",
             ),
             // GPT-5.6 系列（Sol / Terra / Luna，2026-06 发布）
-            ("gpt-5.6-sol", "GPT-5.6 Sol", "5", "30", "0.50", "0"),
-            ("gpt-5.6-terra", "GPT-5.6 Terra", "2.50", "15", "0.25", "0"),
-            ("gpt-5.6-luna", "GPT-5.6 Luna", "1", "6", "0.10", "0"),
+            // 5.6 家族起 cache write 收 1.25× 输入价（此前 GPT 模型写缓存免费，勿回填旧系列）
+            ("gpt-5.6-sol", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            (
+                "gpt-5.6-terra",
+                "GPT-5.6 Terra",
+                "2.50",
+                "15",
+                "0.25",
+                "3.125",
+            ),
+            ("gpt-5.6-luna", "GPT-5.6 Luna", "1", "6", "0.10", "1.25"),
+            // 裸名 gpt-5.6 是 sol 的官方别名；effort 后缀对齐 gpt-5.5 系列的记账形态
+            ("gpt-5.6", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            ("gpt-5.6-low", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            ("gpt-5.6-medium", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            ("gpt-5.6-high", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            ("gpt-5.6-xhigh", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
+            ("gpt-5.6-minimal", "GPT-5.6 Sol", "5", "30", "0.50", "6.25"),
             // GPT-5.5 系列
             ("gpt-5.5", "GPT-5.5", "5", "30", "0.50", "0"),
             ("gpt-5.5-low", "GPT-5.5", "5", "30", "0.50", "0"),
@@ -2248,6 +2263,44 @@ impl Database {
 
     fn repair_current_model_pricing(conn: &Connection) -> Result<(), AppError> {
         let pricing_fixes = [
+            // 2026-07-12 GPT-5.6 家族 cache write=1.25× 输入价（OpenAI 5.6 起的新规），
+            // 修正早期 seed 的 0 值；只匹配未被用户改过的行
+            (
+                "gpt-5.6-sol",
+                "GPT-5.6 Sol",
+                "5",
+                "30",
+                "0.50",
+                "6.25",
+                "5",
+                "30",
+                "0.50",
+                "0",
+            ),
+            (
+                "gpt-5.6-terra",
+                "GPT-5.6 Terra",
+                "2.50",
+                "15",
+                "0.25",
+                "3.125",
+                "2.50",
+                "15",
+                "0.25",
+                "0",
+            ),
+            (
+                "gpt-5.6-luna",
+                "GPT-5.6 Luna",
+                "1",
+                "6",
+                "0.10",
+                "1.25",
+                "1",
+                "6",
+                "0.10",
+                "0",
+            ),
             // 2026-06-10 全量核价（厂商官方 list 价；CNY 按 ~7.14 折算）
             // GLM 4.6/4.7：旧值是中转/OpenRouter 折扣价，统一到 Z.ai 官方（与 glm-5/5.1 一致）
             (