Fix pyright typing for replay export tests and guard meta access

[AlexanderOnischenko]

Motivation

• Address Pyright/type-checker errors about untyped capsys/caplog fixtures and an optional member access on replay event meta reported in src/fetchgraph/replay/export.py and test files.

Description

• Add explicit pytest fixture typing imports and annotations using CaptureFixture[str] and LogCaptureFixture in the replay export tests to satisfy static typing.
• Protect metadata access in format_replay_case_matches by normalizing meta = event.get("meta") to an empty dict when it's not a dict, avoiding optional member access on None.

Testing

• No automated tests were run as part of this change.

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Codex Task