fix: comprehensive JSON Schema sanitization for Claude to Gemini

- Add SanitizeSchemaForGemini utility handling union types, allOf, exclusiveMinimum
- Fix both gemini-cli and gemini API translators
- Resolve "Proto field is not repeating, cannot start list" errors
- Maintain backward compatibility with fallback logic

This fixes Claude Code CLI compatibility issues when using tools with either
Gemini CLI credentials or direct Gemini API keys by properly sanitizing
JSON Schema fields that are incompatible with Gemini's Protocol Buffer validation.

internal/translator/gemini-cli/claude/gemini-cli_claude_request.go

@@ -136,8 +136,14 @@ func ConvertClaudeRequestToCLI(modelName string, inputRawJSON []byte, _ bool) []
 			inputSchemaResult := toolResult.Get("input_schema")
 			if inputSchemaResult.Exists() && inputSchemaResult.IsObject() {
 				inputSchema := inputSchemaResult.Raw
-				inputSchema, _ = sjson.Delete(inputSchema, "additionalProperties")
-				inputSchema, _ = sjson.Delete(inputSchema, "$schema")
+				// Use comprehensive schema sanitization for Gemini API compatibility
+				if sanitizedSchema, sanitizeErr := util.SanitizeSchemaForGemini(inputSchema); sanitizeErr == nil {
+					inputSchema = sanitizedSchema
+				} else {
+					// Fallback to basic cleanup if sanitization fails
+					inputSchema, _ = sjson.Delete(inputSchema, "additionalProperties")
+					inputSchema, _ = sjson.Delete(inputSchema, "$schema")
+				}
 				tool, _ := sjson.Delete(toolResult.Raw, "input_schema")
 				tool, _ = sjson.SetRaw(tool, "parameters", inputSchema)
 				var toolDeclaration any