test: enable mypy typing checks for test/components/writers/

[Aryan-Pardeshi]

Fixes #10396

Context

Part of the ongoing effort (#10396) to incrementally enable mypy typing checks across test directories.

Changes

• Added \ est/components/writers/\ to the \ ypes\ script target list in \pyproject.toml.
• Fixed a type error in \ est/components/writers/test_document_writer.py\ (\ est_run_async_invalid_docstore) where \DocumentWriter\ was passed the \mocked_docstore_class\ reference rather than an instance \mocked_docstore_class().
• All 13 tests in \ est/components/writers/\ pass and mypy reports 0 errors.

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Project	Deployment	Actions	Updated (UTC)
haystack-docs	Ready	Preview	Aug 10, 2026 1:53pm

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Coverage report

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/core/pipeline
pipeline.py
Project Total

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