[fragment-matcher] fix: satisfy strict mode in fragment-matcher (#4683)

[eddeee888]

Description

This fixes the 13 strict: true type errors in @graphql-codegen/fragment-matcher, as part of the strict-mode checklist in #10985. All changes are in packages/plugins/other/fragment-matcher/src/index.ts and are types only:

• TS18048 / TS2345: PluginFunction declares the 4th parameter info as optional, so info.outputFile fails under strictNullChecks. The plugin now reads info?.outputFile.
• TS7006 (6): the introspection result was cast as any, which left the filter, sort and reduce callbacks untyped. It's now typed as ExecutionResult<IntrospectionResultData> (cast through unknown, because graphql's ObjMap result doesn't overlap an interface without an index signature). createPossibleTypesCollection has typed params and a return type. possibleTypes is non-null-asserted there because unions and interfaces always have it.
• TS2454 (5): in the TS output path, typename and type are only assigned when apolloClientVersion is 2 or 3. They're now typed string | undefined.

Generated output doesn't change, so there's no changeset, matching #10988 and #10989. The TS path still prints undefined when apolloClientVersion is neither 2 nor 3, while the JSON/JS paths treat any value other than 2 as v3. That bug stays as it is, because this PR keeps to type-only fixes.

Related #4683

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• pnpm exec tsc --noEmit passes with the current master tsconfig.
• With the strict tsconfig from chore: enable strict: true in root tsconfig (#4683) #10985, tsc --noEmit now reports 0 errors under packages/plugins/other/fragment-matcher (it was 13). The total goes from 283 to 270.
• pnpm exec vitest run packages/plugins/other/fragment-matcher: 14/14 pass.

Further comments

Once this merges, tick plugins/other/fragment-matcher in the #10985 checklist.

🤖 Generated with Claude Code

https://claude.ai/code/session_01MzUSkE6kGAfWan8VDUSkNt

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Generated by Claude Code

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Latest commit: 8acae53

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🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@graphql-codegen/visitor-plugin-common	7.2.8-alpha-20260930103212-8acae536966e3b61933a088b608dafd579610d8a	npm ↗︎ unpkg ↗︎
@graphql-codegen/typescript-operations	6.1.10-alpha-20260930103212-8acae536966e3b61933a088b608dafd579610d8a	npm ↗︎ unpkg ↗︎
@graphql-codegen/client-preset	6.2.1-alpha-20260930103212-8acae536966e3b61933a088b608dafd579610d8a	npm ↗︎ unpkg ↗︎
@graphql-codegen/plugin-helpers	7.4.1-alpha-20260930103212-8acae536966e3b61933a088b608dafd579610d8a	npm ↗︎ unpkg ↗︎