docs: make v0.2 deployment, architecture and API guidance accurate

[script3r]

The documentation described the in-memory partition path as production ingest, advertised unverified performance/GPU gains, and included incomplete setup and recovery examples. This update aligns the guides, API docs, protocol comments and operational examples with the persistent v0.2.0 implementation.

• Explain temporal matching and candidate limits, canonical query identities, durable ingestion, recovery costs, actual configuration wiring and unbounded authoritative memory.
• Correct checkpoint retry consistency, replica restore provenance, topology upgrade and container storage guidance. Unsupported GPU projections are replaced with explicitly unimplemented feasibility notes.
• Provide runnable persistent quick starts and a complete library example. The distributed example accepts a router URI and reconciles before querying. Correct invalid load-test profiling guidance.
• Compile the crate quick start as a doctest and build API documentation with warnings denied in CI.

Validation: strict Rustdoc build, four doctests, Rust 1.98 Clippy, release-package verification, formatting, actionlint, shell/TOML/relative-link checks; executed the README library example, three-shard quick start, 60-record distributed example, and five-shard load-test recipe with 1,000,000 records acknowledged. Full regression suite passed: 357 tests, zero failures, one intentionally ignored timing diagnostic. PR CI passed all three jobs: MSRV, build/test/documentation/package/manifests, and production container image.

The engine and storage algorithms are unchanged. The published v0.2.0 tag and crate remain unchanged.