1.0.0-rc.3

Release candidate for ArtifactFS 1.0.

This supersedes 1.0.0-rc.2. The rc.2 tag was cut before the PR branch's required Go 1.25 modernize fix landed; rc.3 points at the merged, build-passing main commit.

Changes since 1.0.0-rc.1:

- Update Go dependencies, including `modernc.org/sqlite` to v1.53.0, `github.com/jacobsa/fuse` to the 2026-06-03 revision, and `github.com/urfave/cli` to v1.22.17.
- Update the Cloudflare Sandbox SDK example dependencies, including `@cloudflare/sandbox` to 0.12.2, `wrangler` to 4.105.0, Workers types to 4.20260626.1, TypeScript to 6.0.3, and Node types to 26.0.1.
- Include the async hydration performance fixes and overlay/stat-cache fixes that landed after rc.1.
- Apply the Go 1.25 modernize updates required by CI for hydrator tests and benchmarks.

Potential breaking changes:

- ArtifactFS now requires Go 1.25+ to build. The updated `modernc.org/sqlite` stack declares Go 1.25, and the README has been updated to match.
- The sandbox example now tracks newer pre-1.0 `@cloudflare/sandbox` packages. Pre-1.0 minor releases can include API changes, so downstream examples copied from this package should re-run type checks.
- The example type environment moved to TypeScript 6 and `@types/node` 26. That can expose stricter type errors in copied or extended example code.

Verification:

- PR #25 Build & Test passed on the merged branch content.
- PR #25 CodeQL and Semgrep checks passed.
- Local verification before merge: `go build ./cmd/artifact-fs`, `go vet ./...`, `go test ./...`, and `npm run typecheck` in `examples/cloudflare-sandbox-sdk`.