fix: exclude binary and large files from LLM analysis

[Makia9879]

Summary

Skip image, audio, and video files when creating LLM analysis batches.

Changes

• Add a list of supported media file extensions.
• Exclude matching media files from LLMAnalyzerBase.get_batches().
• Add regression tests for media filtering.
• Preserve existing behavior for source files and SVG content.

Verification

• 1393 passed
• 12 skipped
• 6 xfailed
• Ruff lint and formatting checks passed.

[rng1995]

[Automated SkillSpector Review]

Requesting changes because the filter uses attacker-controlled filename suffixes as a binary predicate and does not implement the PR title's large-file exclusion. A text payload named .png is removed from semantic analysis, while extensionless binaries and arbitrarily large text files are still batched. Please base skipping on inspected content or trusted metadata, define and test the size rule, and preserve scan-completeness accounting for skipped files.