[codeandsolder]

Use rust-web-fullstack as the first real consumer test of the rust-skills2 Rust 1.88 → 1.99 migration guidance.

Durable changes

• move the repository toolchain/current-stable CI from Rust 1.98.1 to 1.99.0
• keep the Rust 1.94 / patched 1.94.1 MSRV contract unchanged
• compile production Docker images and the leptosfmt helper with Rust 1.99.0
• refresh docs that distinguish current stable from MSRV
• keep the frozen Cargo.lock; dependency upgrades are deliberately separate
• make local patched crates available during cargo-chef dependency cooks
• fix one strict-nightly doc-markdown diagnostic

Cargo 1.99 feature audit

No Edition-2024 member uses { workspace = true, default-features = false }, so Cargo 1.99's inherited-feature behavior change does not alter this workspace's feature graph.

Migration findings

Stable Rust 1.99 required no application source changes.

The migration full-matrix run passed:

• Rust 1.94.1 native + hydration MSRV checks
• Rust 1.99 lockfile + rustfmt
• Rust 1.99 native Clippy and workspace library tests
• both real wasm32-unknown-unknown hydration links
• dependency audit
• production Leptos builds
• gateway, live-search, and i18n-demo Docker images
• Chromium/PostgreSQL browser + integration E2E
• SQLx OpenTelemetry parent-span verification
• rust-skills2 strict nightly gate

The expanded validation did expose two independent pre-existing/drifting issues:

1. all Docker cargo-chef cooks were missing the workspace's local third-party/ path patches; the dependency layer now copies those sources before cargo chef cook;
2. latest nightly Clippy tightened doc_markdown for one proptest comment; fixed directly.

The temporary migration-only release-matrix expansion has been removed. Routine PR CI remains intentionally cheap; release-only MSRV/WASM/audit/production/Docker/E2E jobs are skipped again.