feat: gadfly-reports — findings store + scoreboard daemon

SQLite-backed HTTP store for Gadfly review findings, per-review run timings, and human/Claude grades, with a points-free per-model scoreboard. Pure fact store: it computes no points or rankings (the dashboard maps severity->points client-side and retunes without re-scoring). Findings are content-addressed by location so cross-model reports collapse for consensus; one grade per finding, latest wins. Pure-Go SQLite (CGO-free) + Docker image CI + tests.

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

Dockerfile

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+# gadfly-reports daemon image. modernc.org/sqlite is pure Go, so the binary is
+# CGO-free and the final image needs no libc / no C toolchain at build time.
+FROM golang:1.26 AS build
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/gadfly-reports .
+
+FROM alpine:3.20
+RUN adduser -D -u 10001 app && mkdir -p /data && chown app /data
+COPY --from=build /out/gadfly-reports /usr/local/bin/gadfly-reports
+USER app
+ENV GADFLY_REPORTS_ADDR=:8090 \
+    GADFLY_REPORTS_DB=/data/gadfly-reports.db
+EXPOSE 8090
+VOLUME ["/data"]
+ENTRYPOINT ["/usr/local/bin/gadfly-reports"]
+CMD ["serve"]