Ship atomic patches, paginated reads, and v0.2.0

[kcsfelty]

Outcome

Ships the v0.2.0 package work needed to resolve every open issue:

• adds atomic quad patches with optimistic required-quad guards, rollback, concurrency, payload, and RDF-term coverage;
• adds opt-in keyset pagination, cancellation, observations, all-pattern equivalence, workerd coverage, and benchmark evidence;
• removes the redundant SPOG index after SQLite and workerd query-plan proof, adds migration 0002, and documents the deferred dictionary prototype;
• updates public npm, integration, security, readiness, and release documentation;
• adds an executable, site-owned Wikibase-style statement example without core ontology coupling;
• closes SQL algebra pushdown as not planned at sourceFactory because that RDF/JS boundary receives individual patterns rather than whole algebra; a future actor/engine RFC remains possible.

Validation

• npm run check (104 tests; coverage gates; Worker; packed consumer; licenses; readiness)
• npm run conformance (490/490 applicable cases)
• npm run benchmark:check (10 scenarios)
• npm run benchmark:storage:check
• GITHUB_REPOSITORY_VISIBILITY=public npm run release:check -- v0.2.0

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