Fix cargo binary install conflicts in CI

[ChristianPavilonis]

Summary

• fix CI failures caused by caching ~/.cargo/bin/ and then reinstalling Cargo binaries
• remove the cached Cargo bin directory from workflow caches to avoid stale installed executables
• force the Viceroy install step so repeat installs do not fail when the binary already exists

Changes

Crate / File	Change
.github/workflows/test.yml	Removed ~/.cargo/bin/ from the cache path list and changed cargo install viceroy --locked to cargo install viceroy --locked --force
.github/workflows/format.yml	Removed ~/.cargo/bin/ from the cache path list

Closes

Closes #249

Test plan

• cargo test --workspace --all-targets
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo check --workspace --all-targets --features "fastly cloudflare"
• WASM builds: wasm32-wasip1 (Fastly) / wasm32-unknown-unknown (Cloudflare)
• Manual testing via edgezero-cli dev
• Other: reviewed the workflow diff locally; this PR only changes GitHub Actions YAML

Checklist

• Changes follow CLAUDE.md conventions
• No Tokio deps added to core or adapter crates
• Route params use {id} syntax (not :id)
• Types imported from edgezero_core (not http crate)
• New code has tests
• No secrets or credentials committed

[aram356]

👍 Looks good