chore: raise coverage thresholds to match 100% achievement

statements: 99 → 100, lines: 99 → 100, functions: 99 → 100,
branches: 94 → 98 (remaining gap is v8-ignored defensive branches)

Author: jdalton

.config/vitest.config.mts

@@ -110,10 +110,10 @@ export default defineConfig({
       skipFull: false,
       ignoreClassMethods: ['constructor'],
       thresholds: {
-        branches: 94, // Lower due to unreachable defensive branches (String(e) when httpGetJson always throws Error)
-        functions: 99,
-        lines: 99,
-        statements: 99,
+        branches: 98,
+        functions: 100,
+        lines: 100,
+        statements: 100,
       },
       // Coverage should report on src files.
       reportsDirectory: './coverage',