feat: add 'Extract to fragment' refactor

[JoviDeCroock]

What/Why

Adds an "Extract to fragment" refactor to the language service. When a selection inside a graphql() document's selection set covers one or more complete sibling field selections, the plugin offers an "Extract to fragment" action under the existing "GraphQL" refactor group. Applying it:

1. inserts a new const <parentType>Fields = graphql(…) fragment document above the statement containing the current call (above its leading comments), named <ParentType>Fields after the selected fields' parent type, with a numeric suffix if that fragment name is already used by a document in the file (or the derived variable name already occurs in the file),
2. replaces the selected fields with a ...<FragmentName> spread, and
3. appends the new fragment variable to the call's fragment array second argument, or adds , [<var>] when the call only has the document argument.

This makes it much easier to progressively split large gql.tada documents into co-located fragments.

Implementation notes

• packages/graphqlsp/src/extractFragment.ts implements both applicability (canExtractFragment) and the edits (getExtractFragmentEdits). The TS selection range is mapped into the document text (getStart() + 1 offset mapping, as in definition.ts), trimmed of GraphQL ignored tokens (whitespace/commas), and validated against the parsed document AST: the trimmed range must start at a field selection and consecutive sibling fields must tile it exactly (a selection ending inside a field, crossing a selection-set boundary, or covering non-field selections is rejected).
• The parent type is resolved by walking the document with graphql's TypeInfo; the schema is resolved per document via getSchemaForName using the document's schema name, the same way diagnostics.ts does, so multi-schema setups pick the right schema.
• The generated statement mirrors the current call's callee text and quote/backtick style, detects the file's indentation unit from the document's own lines, and re-indents the extracted fields (preserving nested selection-set indentation). Single/double-quoted documents are extracted as a single-line fragment since those literals can't span lines.
• index.ts now dispatches getEditsForRefactor by refactor/action name (instead of the previous early-return for the persisted-operations code fix) and getApplicableRefactors merges all applicable actions into one "GraphQL" refactor group. Everything stays behind the guard() fallback so exceptions never propagate into tsserver.
• If the call's second argument exists but isn't an array literal (e.g. an identifier), the refactor isn't offered, since the fragment reference couldn't be added safely.

Test plan

• New e2e suite test/e2e/extract-fragment.test.ts (new fixture test/e2e/fixture-project-tada/fixtures/extract-fragment.ts), driving a real tsserver via the getApplicableRefactors/getEditsForRefactor protocol commands:
  • action offered for a selection covering complete sibling fields (including leading/trailing whitespace trimming),
  • action NOT offered for a selection ending mid-field, one crossing a nested selection-set boundary, and a collapsed selection,
  • edits applied to the fixture content and asserted via full-file inline snapshots for: extraction appending to an existing fragment array (with <ParentType>Fields name collision resolving to PokemonFields2), extraction of a field with a nested selection set at the end of a run, and extraction from a call without a fragment array (adds , [pokemonFields2]).
• pnpm --filter @0no-co/graphqlsp run build passes.
• Full pnpm run test:e2e: 12 test files, 59 tests, all passing.

Limitations

• The refactor is only offered in call-expression mode (templateIsCallExpression: true, the default, i.e. gql.tada-style graphql() calls). Tagged-template mode is not supported, since fragments there aren't composed through a fragment-array argument.
• Only plain field selections can be extracted; runs containing fragment spreads or inline fragments are not offered the refactor.
• The refactor requires the schema to be loaded to resolve the selection's parent type, so it may not be offered immediately after project start.

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Latest commit: cc50966

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

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Name	Type
@0no-co/graphqlsp	Minor

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