feat: env-defined endpoint aliases (http-capable, local Ollama friendly)

majordomo's built-in LLM_* env DSNs are HTTPS-only (DSN.BaseURL forces https),
so they can't express a plaintext local Ollama. Add Gadfly-native env families
that register named providers/aliases with majordomo before resolution:

  GADFLY_ENDPOINT_<NAME>="<provider>|<base-url>[|<key>]"  # base URL verbatim (http ok)
  GADFLY_ALIAS_<NAME>="<majordomo spec>"                  # plain alias / failover chain

Then reference them as "<name>/<model>" (or the bare alias) in GADFLY_MODEL(S).
<NAME> lowercases to the registry name, matching majordomo's LLM_* convention.
LLM_* DSNs still work (and are documented) for HTTPS endpoints. + unit tests,
README "Endpoint aliases via env vars", stub example.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

examples/adversarial-review.yml

@@ -61,6 +61,11 @@ jobs:
           #   OpenAI / Anthropic / Google (supported via majordomo, UNTESTED — see README):
           #     GADFLY_PROVIDER: openai      # then set OPENAI_API_KEY below
           #     OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+          #
+          #   Named endpoint aliases (reference as name/model in GADFLY_MODELS).
+          #   vars/secrets aren't auto-exposed, so map each one explicitly:
+          #     GADFLY_ENDPOINT_BIGBOX: ${{ vars.GADFLY_ENDPOINT_BIGBOX }}  # "ollama|http://192.168.1.50:11434"
+          #     GADFLY_MODELS: bigbox/qwen2.5-coder:7b
           GADFLY_PROVIDER: ${{ vars.GADFLY_PROVIDER }}
           GADFLY_BASE_URL: ${{ vars.GADFLY_BASE_URL }}
           GADFLY_MODELS: ${{ vars.GADFLY_MODELS }}