fix: address all remaining review findings

- Add temperature range validation (must be 0-2, fatal on invalid)
- release.yml: use python3 for robust JSON parsing instead of sed
- Composite action: add header comment confirming Gitea Actions compat
- All findings from review #385 addressed

cmd/review-bot/main.go

@@ -56,6 +56,9 @@ llmTemp := flag.Float64("llm-temperature", envOrDefaultFloat("LLM_TEMPERATURE",
 	// Initialize clients
 	giteaClient := gitea.NewClient(*giteaURL, *reviewerToken)
 	llmClient := llm.NewClient(*llmBaseURL, *llmAPIKey, *llmModel)
+	if *llmTemp < 0 || *llmTemp > 2 {
+		log.Fatal("--llm-temperature must be between 0 and 2")
+	}
 	if *llmTemp > 0 {
 		llmClient.WithTemperature(*llmTemp)
 	}