Emit named GraphQL operations for generated tools

[oscnord]

Problem

Generated GraphQL operations are anonymous — e.g. query($slug: ID!) { contentcollection(slug: $slug) { ... } }. Two consequences:

• Servers that require named operations reject every invocation. (Apollo Server can be configured this way; some gateways enforce it unconditionally and return a 400 before the resolver runs.)
• APM/observability tooling (Apollo Studio, New Relic, Datadog) keys traces and transaction names off the operation name, so all anonymous operations collapse into a single unnamed bucket.

Change

Derive an operation name from the root field and emit it in the generated document, so contentcollection produces:

query Contentcollection($slug: ID!) { contentcollection(slug: $slug) { ... } }

• buildOperationStringForField and the anonymous fallback path both name the operation.
• The name is the root field name with its first character upper-cased; GraphQL field names are already valid name tokens, so no further escaping is needed.
• Each generated document contains exactly one operation, so there is no naming-collision concern.
• The request body is unchanged otherwise; servers derive operationName from the document, so no separate operationName field is required.

Tests

Added a test asserting a query and a mutation are sent as named operations (query Hello …, mutation SetGreeting …). Full @executor-js/plugin-graphql suite passes; typecheck, oxfmt, and oxlint are clean.

[RhysSullivan]

Rebased this onto current main and fixed the stale test setup plus changeset target.\n\nValidation run locally on the rebased branch:\n- bun run --cwd packages/plugins/graphql test\n- bun run --cwd packages/plugins/graphql typecheck\n- bunx changeset status --since=origin/main\n- bun run format:check -- .changeset/named-graphql-operations.md packages/plugins/graphql/src/sdk/plugin.ts packages/plugins/graphql/src/sdk/plugin.test.ts