feat: specialist suite — configurable + custom review lenses (one consolidated comment)

Replace the single generic review with a suite of focused specialists, each its
own review+recheck pass, merged into ONE comment (a collapsible section per lens,
led by the worst verdict; the optional `improvements` lens never escalates it).

- cmd/gadfly/specialists.go: built-in lenses + default suite (security, correctness,
  maintainability, performance, error-handling) + opt-in (tests, docs, conventions,
  improvements). Selection via GADFLY_SPECIALISTS (csv/"all"); custom defs via
  GADFLY_SPECIALIST_<NAME> env and a repo .gadfly.yml (specialists + define).
  Precedence: built-ins < file < env. Unknown names error but don't sink the run.
- cmd/gadfly/consolidate.go: verdict parse + one-comment render.
- main.go: loop specialists; per-lens failure is an inline notice, never fatal.
  Default timeout bumped to 600s (suite runs sequentially).
- base system prompt trimmed to persona+tools+discipline+output; lens-specific
  focus is appended per specialist (semantic re-derivation discipline kept in base).
- entrypoint default models -> single model (suite already gives breadth; cost ~=
  specialists × models × 2). Adds gopkg.in/yaml.v3.
- docs/examples: README "Specialists" section, examples/.gadfly.yml, stub var,
  CLAUDE.md architecture/config. Dynamic `auto` selection is the planned next step.

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

examples/.gadfly.yml

@@ -0,0 +1,34 @@
+# Optional per-repo Gadfly config. Place at the repo ROOT as `.gadfly.yml`
+# (or point GADFLY_CONFIG at it). It's read from the PR's checked-out tree, so
+# it's version-controlled and reviewed like any other file.
+#
+# Precedence for specialist DEFINITIONS: built-ins < this file < GADFLY_SPECIALIST_* env.
+# Precedence for SELECTION: GADFLY_SPECIALISTS env > this file's `specialists:` > default suite.
+
+# Which specialists run. Omit this key to use the default suite
+# (security, correctness, maintainability, performance, error-handling).
+# Built-in opt-ins you can add: tests, docs, conventions, improvements. Or "all".
+specialists:
+  - security
+  - correctness
+  - maintainability
+  - tests
+  - migrations   # a custom one, defined below
+
+# Add new specialists, or override a built-in by reusing its name (e.g. give
+# `security` a repo-specific focus). `focus` is appended to the base reviewer
+# prompt as that lens's instruction.
+define:
+  - name: migrations
+    title: "🗃️ DB migrations"
+    focus: >
+      Review database schema migrations for destructive operations (DROP/ALTER
+      that loses data), missing or unindexed foreign keys, non-idempotent steps,
+      and changes that would lock a large table on deploy. Check that any new
+      column added to a domain struct is wired through every storage layer.
+  - name: security
+    title: "🔒 Security (house rules)"
+    focus: >
+      In addition to the usual security review, this repo requires: all web
+      routes use the auth middleware, no secrets in logs, and all external HTTP
+      calls set a timeout. Flag any violation.

examples/README.md

@@ -10,6 +10,7 @@ set the secrets/vars it references. Gadfly is advisory only — it never blocks
 | [`local-ollama.yml`](local-ollama.yml) | a **local/LAN Ollama** daemon | nothing (or `GADFLY_BASE_URL` for a remote host) |
 | [`openai-compatible.yml`](openai-compatible.yml) | any **OpenAI-compatible** endpoint (local Ollama `/v1`, gateway, vLLM, OpenRouter…) | `GADFLY_BASE_URL` (+ a key for most gateways) |
 | [`endpoint-aliases.yml`](endpoint-aliases.yml) | **several named backends** at once (one comment each) | repo vars `GADFLY_ENDPOINT_<NAME>` |
+| [`.gadfly.yml`](.gadfly.yml) | **per-repo specialist config** (not a workflow — goes at your repo root) | — |
 
 Common to all:
 - **Triggers:** new/reopened/ready non-draft PR (auto), `@gadfly review` comment (allowed users),

examples/adversarial-review.yml

@@ -43,6 +43,11 @@ jobs:
           OLLAMA_CLOUD_API_KEY: ${{ secrets.OLLAMA_CLOUD_API_KEY }}
           OLLAMA_REVIEW_MODELS: ${{ vars.OLLAMA_REVIEW_MODELS }}
           GADFLY_ALLOWED_USERS: ${{ vars.GADFLY_ALLOWED_USERS }}
+          # Specialist suite (optional). Empty = default suite
+          # (security,correctness,maintainability,performance,error-handling).
+          # csv to choose; "all" for everything; or define custom ones via a repo
+          # .gadfly.yml / GADFLY_SPECIALIST_<NAME>. See README "Specialists".
+          GADFLY_SPECIALISTS: ${{ vars.GADFLY_SPECIALISTS }}
           # --- Models & providers (optional; default = Ollama Cloud) ----------
           # Gadfly is majordomo-powered, so it can target other backends. Set a
           # provider for bare model ids; point at a different endpoint with a