Add basic set operations to Graph

[fubhy]

Split from #6394. Original implementation by @lloydrichards.

Adds the basic graph set operations:

• Graph.compose
• Graph.intersection
• Graph.difference
• Graph.symmetricDifference

Includes runtime tests, type tests, JSDoc examples, and the dedicated changeset.

This is PR 1 of 3 in the split stack.

[changeset-bot]

🦋 Changeset detected

Latest commit: e08e930

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
effect	Major
@effect/opentelemetry	Major
@effect/platform-browser	Major
@effect/platform-bun	Major
@effect/platform-node-shared	Major
@effect/platform-node	Major
@effect/vitest	Major
@effect/ai-anthropic	Major
@effect/ai-openai-compat	Major
@effect/ai-openai	Major
@effect/ai-openrouter	Major
@effect/atom-react	Major
@effect/atom-solid	Major
@effect/atom-vue	Major
@effect/sql-clickhouse	Major
@effect/sql-d1	Major
@effect/sql-libsql	Major
@effect/sql-mssql	Major
@effect/sql-mysql2	Major
@effect/sql-pg	Major
@effect/sql-pglite	Major
@effect/sql-sqlite-bun	Major
@effect/sql-sqlite-do	Major
@effect/sql-sqlite-node	Major
@effect/sql-sqlite-react-native	Major
@effect/sql-sqlite-wasm	Major
@effect/openapi-generator	Major

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