chore: coverage fixups

[horsefacts]

Motivation

Recent coverage reports show a couple uncovered lines in StorageRent and FnameResolver.

Change Summary

Add a test for the selector check in FnameResolver and the initial price update in StorageRent.

Merge Checklist

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• The PR title adheres to the conventional commits standard
• The PR has been tagged with change type label(s) (i.e. documentation, feature, bugfix, or chore)
• The PR's changes adhere to all the requirements in the contribution guidelines
• This PR does not require changes to the Farcaster protocol

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PR-Codex overview

Focus of the PR:

This PR focuses on adding a new test function testFuzzResolveRevertsNonAddrFunction and updating an existing test function testInitialPriceUpdate.

Detailed summary:

• Added a new test function testFuzzResolveRevertsNonAddrFunction in the FnameResolver contract.
• Updated the testInitialPriceUpdate function in the StorageRent contract.

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[github-actions]

Coverage after merging horsefacts/coverage-fixups into main will be

98.62%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
Bundler.sol	100%	100%	100%	100%
FnameResolver.sol	100%	100%	100%	100%
IdRegistry.sol	100%	100%	100%	100%
KeyRegistry.sol	100%	100%	100%	100%
StorageRent.sol	100%	100%	100%	100%
src/lib
TransferHelper.sol	0%	0%	0%	0%	15, 15, 15, 25–26, 26, 26