Fix missing channel

[mrkbac]

This fixes:

    raise McapError(f'no channel record found with id {record.channel_id}')
mcap.exceptions.McapError: no channel record found with id 3

[Copilot]

Pull Request Overview

This PR fixes a bug where the McapError "no channel record found with id X" was being raised incorrectly. The fix moves the channel existence check to occur after filtering logic and allows pre-existing schemas and channels to be passed into the _read_inner function.

• Moved channel existence validation to occur after message filtering logic
• Added optional schemas and channels parameters to _read_inner function
• Updated the function call to pass summary schemas and channels when available

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[Copilot]

This line will raise a KeyError if the channel_id is not in _channels, but the validation check that prevents this error is now placed after this line (at line 140-141). The validation should occur before attempting to access the channel.

[Copilot]

This validation check is now unreachable because line 133 will already raise a KeyError if the channel_id doesn't exist in _channels. The check should be moved before line 133 to be effective.

[siliconlad]

Add a test for this? Otherwise LGTM!