fix(translator): strip defer_loading from Claude tool declarations in Codex and Gemini translators

Claude's Tool Search feature (advanced-tool-use-2025-11-20 beta) adds
defer_loading field to tool definitions. When proxying Claude requests
to Codex or Gemini, this unknown field causes 400 errors upstream.

Strip defer_loading (and cache_control where missing) in all three
Claude-to-upstream translation paths:
- codex/claude: defer_loading + cache_control
- gemini-cli/claude: defer_loading
- gemini/claude: defer_loading

Fixes #1725, Fixes #1375

internal/translator/codex/claude/codex_claude_request.go

@@ -255,6 +255,8 @@ func ConvertClaudeRequestToCodex(modelName string, inputRawJSON []byte, _ bool)
 			tool, _ = sjson.SetRaw(tool, "parameters", normalizeToolParameters(toolResult.Get("input_schema").Raw))
 			tool, _ = sjson.Delete(tool, "input_schema")
 			tool, _ = sjson.Delete(tool, "parameters.$schema")
+			tool, _ = sjson.Delete(tool, "cache_control")
+			tool, _ = sjson.Delete(tool, "defer_loading")
 			tool, _ = sjson.Set(tool, "strict", false)
 			template, _ = sjson.SetRaw(template, "tools.-1", tool)
 		}

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

@@ -156,6 +156,7 @@ func ConvertClaudeRequestToCLI(modelName string, inputRawJSON []byte, _ bool) []
 				tool, _ = sjson.Delete(tool, "input_examples")
 				tool, _ = sjson.Delete(tool, "type")
 				tool, _ = sjson.Delete(tool, "cache_control")
+				tool, _ = sjson.Delete(tool, "defer_loading")
 				if gjson.Valid(tool) && gjson.Parse(tool).IsObject() {
 					if !hasTools {
 						out, _ = sjson.SetRaw(out, "request.tools", `[{"functionDeclarations":[]}]`)

internal/translator/gemini/claude/gemini_claude_request.go

@@ -137,6 +137,7 @@ func ConvertClaudeRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 				tool, _ = sjson.Delete(tool, "input_examples")
 				tool, _ = sjson.Delete(tool, "type")
 				tool, _ = sjson.Delete(tool, "cache_control")
+				tool, _ = sjson.Delete(tool, "defer_loading")
 				if gjson.Valid(tool) && gjson.Parse(tool).IsObject() {
 					if !hasTools {
 						out, _ = sjson.SetRaw(out, "tools", `[{"functionDeclarations":[]}]`)