refactor(store): swap mattn/go-sqlite3 for modernc.org/sqlite

Pure-Go SQLite driver — no CGO, no C compiler. Enables:
- static binaries (verified: `file` shows statically linked)
- cross-compile to linux/arm64, darwin/amd64+arm64, windows/amd64+arm64
- goreleaser now builds 6 OS/arch targets + windows .zip
- Dockerfile drops gcc/musl-dev, sets CGO_ENABLED=0
- release-binaries drops gcc/musl-dev

Driver name changes sqlite3 → sqlite, DSN pragmas use
_pragma=name(value) format. All tests pass CGO=0 and CGO=1 -race.

Homebrew cask block removed (was skip_upload:true dead config).

Dockerfile

@@ -1,12 +1,11 @@
 # --- Stage 1: Builder ---
 FROM golang:1.26-alpine3.23@sha256:91eda9776261207ea25fd06b5b7fed8d397dd2c0a283e77f2ab6e91bfa71079d AS builder
-RUN apk add --no-cache gcc musl-dev
 WORKDIR /app
 COPY go.mod go.sum ./
 RUN --mount=type=cache,target=/go/pkg/mod \
     go mod download
 COPY . .
-ENV CGO_ENABLED=1
+ENV CGO_ENABLED=0
 ARG VERSION=dev
 ARG COMMIT=none
 ARG BUILD_DATE=unknown