feat(08-02): add 25 GitHub dorks for frontier and specialized categories

- frontier.yaml: 15 dorks covering Tier 1/2 providers (OpenAI, Anthropic,
  Google AI, Azure OpenAI, AWS Bedrock, xAI, Cohere, Mistral, Groq,
  Together, Replicate)
- specialized.yaml: 10 dorks covering Tier 3 providers (Perplexity,
  Voyage, Jina, AssemblyAI, Deepgram, ElevenLabs, Stability, HuggingFace)
- Extend loader to accept YAML list format in addition to single-dork
  mapping, enabling multi-dork files for Wave 2+ plans
- Mirror all YAMLs into dorks/github/ (user-visible) and
  pkg/dorks/definitions/github/ (go:embed target)

dorks/github/specialized.yaml

@@ -0,0 +1,70 @@
+- id: perplexity-envfile
+  name: "Perplexity API Key in .env files"
+  source: github
+  category: specialized
+  query: 'pplx- extension:env'
+  description: "Finds Perplexity API keys (pplx- prefix) in .env files"
+  tags: [perplexity, env, tier3]
+- id: voyage-envfile
+  name: "Voyage AI API Key in .env files"
+  source: github
+  category: specialized
+  query: 'VOYAGE_API_KEY extension:env'
+  description: "Finds Voyage AI embedding keys in .env files"
+  tags: [voyage, embeddings, env, tier3]
+- id: jina-envfile
+  name: "Jina AI API Key in .env files"
+  source: github
+  category: specialized
+  query: 'jina_ extension:env'
+  description: "Finds Jina AI API keys (jina_ prefix) in .env files"
+  tags: [jina, embeddings, env, tier3]
+- id: assemblyai-envfile
+  name: "AssemblyAI API Key in .env files"
+  source: github
+  category: specialized
+  query: 'ASSEMBLYAI_API_KEY extension:env'
+  description: "Finds AssemblyAI speech-to-text keys in .env files"
+  tags: [assemblyai, speech, env, tier3]
+- id: deepgram-envfile
+  name: "Deepgram API Key in .env files"
+  source: github
+  category: specialized
+  query: 'DEEPGRAM_API_KEY extension:env'
+  description: "Finds Deepgram speech API keys in .env files"
+  tags: [deepgram, speech, env, tier3]
+- id: elevenlabs-envfile
+  name: "ElevenLabs API Key in .env files"
+  source: github
+  category: specialized
+  query: 'ELEVENLABS_API_KEY extension:env'
+  description: "Finds ElevenLabs voice synthesis keys in .env files"
+  tags: [elevenlabs, voice, env, tier3]
+- id: stability-envfile
+  name: "Stability AI Key in .env files"
+  source: github
+  category: specialized
+  query: 'sk-stability- extension:env'
+  description: "Finds Stability AI image generation keys in .env files"
+  tags: [stability, image, env, tier3]
+- id: huggingface-envfile
+  name: "Hugging Face Token in .env files"
+  source: github
+  category: specialized
+  query: 'hf_ extension:env'
+  description: "Finds Hugging Face access tokens (hf_ prefix) in .env files"
+  tags: [huggingface, env, tier3]
+- id: perplexity-config
+  name: "Perplexity Key in config.yaml"
+  source: github
+  category: specialized
+  query: 'pplx- filename:config.yaml'
+  description: "Finds Perplexity API keys hard-coded into config.yaml files"
+  tags: [perplexity, config, tier3]
+- id: deepgram-config
+  name: "Deepgram in .env.local"
+  source: github
+  category: specialized
+  query: 'DEEPGRAM filename:.env.local'
+  description: "Finds Deepgram references in .env.local files (Next.js style)"
+  tags: [deepgram, env, nextjs, tier3]