feat(pricing): add GLM-5.3 to built-in model pricing table (#6591)

Seed glm-5.3 at $1.4/$4.4 per MTok with $0.26 cache read, matching the
official Z.ai list price (identical to the GLM-5.2 tier):
https://docs.z.ai/guides/overview/pricing

New model id, so seed only; no repair entry and no SCHEMA_VERSION bump.
Existing installs pick the row up on next launch via INSERT OR IGNORE, and
the startup cost backfill re-prices historical glm-5.3 rows recorded at $0.

src-tauri/src/database/schema.rs

@@ -2345,6 +2345,7 @@ impl Database {
             ("glm-5", "GLM-5", "1", "3.2", "0.2", "0"),
             ("glm-5.1", "GLM-5.1", "1.4", "4.4", "0.26", "0"),
             ("glm-5.2", "GLM-5.2", "1.4", "4.4", "0.26", "0"),
+            ("glm-5.3", "GLM-5.3", "1.4", "4.4", "0.26", "0"),
             ("glm-5-turbo", "GLM-5-Turbo", "1.2", "4", "0.24", "0"),
             ("glm-5v-turbo", "GLM-5V-Turbo", "1.2", "4", "0.24", "0"),
             // MiMo (小米)