task 009/00i: remove internal translation from image clients; consolidate provider normalization

- task 009: remove translateBulgarianToEnglish from OpenAIClient and
  NanoBananaClient. Image clients no longer make internal translation API calls;
  callers must supply SearchOptions.Translation (processor and GUI already do).
  When translation is absent, opts.Query (the Bulgarian word) is used as
  fallback subject so image generation still proceeds. Update tests to pass
  translation via SearchOptions rather than relying on the removed fallback.
- task 00i: consolidate duplicate ProviderGemini/ProviderOpenAI constants and
  normalizeProvider() functions from internal/translation and internal/phonetic
  into a shared config.NormalizeProvider(string) string in
  internal/config/provider.go. Both packages now delegate to the shared
  function so the normalization rule (lowercase, trim, default "gemini") has
  one authoritative home.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/internal/config/provider.go b/internal/config/provider.go
new file mode 100644
index 0000000..7044964
--- /dev/null
+++ b/internal/config/provider.go
@@ -0,0 +1,24 @@
+package config
+
+import "strings"
+
+const (
+	// ProviderGemini is the canonical name for the Google Gemini provider.
+	// It is the default across all subsystems (audio, translation, phonetic).
+	ProviderGemini = "gemini"
+
+	// ProviderOpenAI is the canonical name for the OpenAI provider.
+	ProviderOpenAI = "openai"
+)
+
+// NormalizeProvider returns a canonical, lowercase provider name.
+// An empty input resolves to ProviderGemini (the default). The function is
+// shared by the audio, translation, and phonetic packages so the same
+// normalization rule has a single authoritative home.
+func NormalizeProvider(provider string) string {
+	normalized := strings.ToLower(strings.TrimSpace(provider))
+	if normalized == "" {
+		return ProviderGemini
+	}
+	return normalized
+}