Initial commit: Breadcrumb GPS trip viewer

Go server receiving Colota location data into SQLite, with a trip-segmentation
API and embedded web frontend for browsing trips on a map.

Dockerfile

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+FROM golang:1.22-alpine AS builder
+
+# gcc is required for go-sqlite3 (CGO)
+RUN apk add --no-cache gcc musl-dev
+
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=1 GOOS=linux go build -o breadcrumb .
+
+# ── Runtime image ─────────────────────────────────────────────────────────────
+FROM alpine:3.19
+RUN apk add --no-cache ca-certificates
+
+WORKDIR /app
+COPY --from=builder /app/breadcrumb .
+
+# Data directory for the SQLite file (mount a volume here)
+RUN mkdir -p /data
+
+EXPOSE 8080
+
+ENTRYPOINT ["./breadcrumb"]
+CMD ["-port", "8080", "-db", "/data/locations.db"]