feat: add Kimi K2.7 Code model and upgrade official Kimi presets

Add kimi-k2.7-code pricing seed (in $0.95 / out $4.00 / cache-read $0.19
per 1M tokens, 256K context) and point all six official Moonshot Kimi
presets (Claude Code, Codex, Claude Desktop, Hermes, OpenCode, OpenClaw)
at the new model. Rename the version-tagged OpenCode/OpenClaw presets to
"Kimi K2.7 Code" and correct the OpenClaw context window to 262144.

The seed is applied via the idempotent INSERT OR IGNORE path that runs on
every startup, so existing users pick up the new pricing without a schema
migration. Kimi For Coding and Nvidia presets are intentionally untouched.

src-tauri/src/database/schema.rs

@@ -1803,6 +1803,14 @@ impl Database {
             ),
             ("kimi-k2.5", "Kimi K2.5", "0.60", "3.00", "0.10", "0"),
             ("kimi-k2.6", "Kimi K2.6", "0.95", "4.00", "0.16", "0"),
+            (
+                "kimi-k2.7-code",
+                "Kimi K2.7 Code",
+                "0.95",
+                "4.00",
+                "0.19",
+                "0",
+            ),
             // MiniMax 系列
             ("minimax-m2.1", "MiniMax M2.1", "0.27", "0.95", "0.03", "0"),
             (