fix: convert schema types to Google uppercase format (fixes #82)

The /compact command was failing with 'Proto field is not repeating,
cannot start list' error for Claude models because tool schemas were
sent with lowercase JSON Schema types (array, object, string) but
Google's Cloud Code API expects uppercase protobuf types (ARRAY,
OBJECT, STRING).

Changes:
- Add toGoogleType() function to convert JSON Schema types to Google format
- Add Phase 5 to cleanSchemaForGemini() for type conversion
- Apply cleanSchemaForGemini() for ALL models (not just Gemini) since
  all requests go through Cloud Code API which validates schema format
- Add comprehensive test suite with 10 tests covering nested arrays,
  complex schemas, and real-world Claude Code tool scenarios

Fixes #82

src/format/request-converter.js

@@ -210,10 +210,11 @@ export function convertAnthropicToGoogle(anthropicRequest) {
             // Sanitize schema for general compatibility
             let parameters = sanitizeSchema(schema);
 
-            // For Gemini models, apply additional cleaning for VALIDATED mode
-            if (isGeminiModel) {
-                parameters = cleanSchemaForGemini(parameters);
-            }
+            // Apply Google-format cleaning for ALL models since they all go through
+            // Cloud Code API which validates schemas using Google's protobuf format.
+            // This fixes issue #82: /compact command fails with schema transformation error
+            // "Proto field is not repeating, cannot start list" for Claude models.
+            parameters = cleanSchemaForGemini(parameters);
 
             return {
                 name: String(name).replace(/[^a-zA-Z0-9_-]/g, '_').slice(0, 64),