ci: check direct minimal versions (#4173)

* ci: check direct minimal versions

Switch minimal-versions CI check to direct-minimal-versions

Avoids failures caused by incorrect lower bounds in transitive
dependencies (e.g. native-tls 0.2.12 declaring openssl ^0.10.29
but requiring >= 0.10.46 for Pkcs12::parse2). direct-minimal-
versions only resolves our own declared lower bounds to their minimums.

* fix: bump direct dependency minimum versions

To eliminate another dep to manage, brought in #4171

All workspace Cargo.toml files bumped direct dependency minimum versions to be compatible with transitive requirements
under direct-minimal-versions:
- memchr 2.4.1 → 2.5.0 (winnow needs ^2.5)
- futures-* → 0.3.31 (futures-util needs futures-core ^0.3.31)
- serde → 1.0.218, serde_json → 1.0.85
- proc-macro2 → 1.0.83, syn → 2.0.87, quote → 1.0.35
- tokio → 1.20.1, time → 0.3.37, uuid → 1.12.1
- smallvec → 1.10.0, bitflags → 2.4, percent-encoding → 2.3.0
- rand → 0.8.5, dotenvy → 0.15.7, plus many others

Aligned all examples to the same minimums, then regenerated
Cargo.lock with normal resolver.

* fix: bump more direct minimums for direct-minimal-versions CI

CI was failing on `cargo +nightly generate-lockfile -Z direct-minimal-versions`
because several declared minimums were too low to satisfy transitive
requirements introduced by upstream's recent updates (axum 0.8, cargo_metadata
0.23, validator 0.20, etc.).

- anyhow 1.0 → 1.0.58 (sqlite/serialize example)
- bytes 1.1.0 → 1.2.0 (axum-core 0.5 needs ^1.2)
- clap 4.3.10 → 4.4.7 (sqlx-cli uses Command::styles / clap::builder::Styles)
- filetime 0.2 → 0.2.25 (sqlx-cli uses FileTime::now())
- itoa 1.0.1 → 1.0.5 (axum 0.8 needs ^1.0.5)
- serde 1.0.218 → 1.0.219 (cargo_metadata 0.23.1 needs ^1.0.219)
- serde_json 1.0.85 → 1.0.142 (cargo_metadata 0.23.1 needs ^1.0.142)
- smallvec 1.10.0 → 1.13.1 (idna 1.0 via validator 0.20 needs ^1.13.1)
- tokio 1.20.1 → 1.25.0 (axum 0.8 needs ^1.25.0)
- tower 0.5 → 0.5.2 (axum 0.8 needs ^0.5.2)