Release prolly-map 0.6.0 and compatible store adapters

[forhappy]

What changed

• fixes the durable snapshot pin leak, worker-width assertion, benchmark sample gate, and UniFFI library placement
• makes the secondary-index benchmark use bounded pages and joins
• aligns the Java parity test with the typed secondary-index error contract
• releases the hard-cutover line as prolly-map 0.6.0 with compatible version bumps for all public store adapters
• raises and enforces the truthful Rust 1.89 minimum
• adds core package verification and a 12-adapter CI test matrix
• adds release notes and updates public dependency examples

Why

The merged secondary-index foundation exposed four required-check failures and additional release gaps during package qualification. This PR fixes those root causes and makes the release metadata, packaged archive, binding contract, and CI gates match the hard-cutover architecture.

Validation

• cargo fmt --all -- --check
• cargo check --all-targets
• cargo clippy --all-targets -- -D warnings
• cargo test --all-targets (501 library tests plus integration tests, benchmarks, and examples)
• RUSTDOCFLAGS='-D warnings' cargo test --doc (74 doctests)
• all 12 store adapter test suites and doctests
• Rust 1.89 cargo check --all-targets
• Turso --all-targets --all-features
• secondary-index cutover and bounded benchmark smoke gates
• JVM, Node, WASM, Python, and Ruby binding gates
• 3,067-operation portable API inventory
• SQLite production indexed-profile tests
• cargo package and packaged-archive content inspection

Registry publication is intentionally deferred until this PR is green and merged.