Bump redb dependency 4.0 → 4.1.0

[aram356]

Description

Update redb workspace dependency from 4.0 to 4.1.0 to pick up upstream improvements and stay current with the latest minor release.

Current vs target

Field	Current	Target
Cargo.toml	4.0	4.1.0
Cargo.lock	4.0.0	4.1.0

Compatibility

• redb 4.1.0 declares MSRV 1.89 — well below the project's 1.91.1 toolchain pin.
• The 4.0.0 → 4.1.0 jump is a minor bump within the existing major (4.x), so no API surface changes affect usage.
• Only consumer in the workspace is crates/edgezero-adapter-axum/src/key_value_store.rs (development KV store). The persistent on-disk file format is the same 4.x layout — existing .edgezero/kv.redb files written by 4.0 remain readable.

Verification (local)

All 5 CI gates pass:

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo test --workspace --all-targets — full suite green
• cargo check --workspace --all-targets --features "fastly cloudflare spin"
• cargo check -p edgezero-adapter-spin --target wasm32-wasip1 --features spin

Out of scope

• spin-sdk 5.2 → 6.0: requires rustc 1.93, blocked on a separate toolchain bump decision.