fix(pricing): correct Kimi K2.6 seed prices to match official rates

Moonshot's official USD pricing for kimi-k2.6 is $0.95 input /
$4.00 output / $0.16 cache-hit per 1M tokens (~58-60% higher than
K2.5). The previous commit copied K2.5's $0.60/$2.50/$0.10, which
would have under-billed K2.6 traffic in the usage dashboard.

No migration needed since this version is unreleased; INSERT OR
IGNORE will write the correct values on first launch.

src-tauri/src/database/schema.rs

@@ -1639,7 +1639,7 @@ impl Database {
                 "0",
             ),
             ("kimi-k2.5", "Kimi K2.5", "0.60", "2.50", "0.10", "0"),
-            ("kimi-k2.6", "Kimi K2.6", "0.60", "2.50", "0.10", "0"),
+            ("kimi-k2.6", "Kimi K2.6", "0.95", "4.00", "0.16", "0"),
             // MiniMax 系列
             ("minimax-m2.1", "MiniMax M2.1", "0.27", "0.95", "0.03", "0"),
             (