Replace parser-fuzzers with cups-filters libFuzzer targets

[kimaiden1984-boop]

Summary

• Replace the parser-fuzzers research prototype with an OSS-Fuzz-ready cups-filters project.
• Add 12 in-process libFuzzer targets covering raw formats, constrained state transitions, PCLX compression, and text output semantics.
• Package one seed corpus and dictionary per target, with OSS-Fuzz runtime options generated during the build.
• Build the current CUPS, PDFio, libcupsfilters, libppd, and cups-filters stack without launching standalone filters or external document interpreters.

The previous Python and AFL++ experiment framework is removed so this directory contains only the files needed to build and run the OSS-Fuzz project.

Testing

Validated after copying parser-fuzzers into a local OSS-Fuzz checkout:

• AddressSanitizer build_fuzzers passed.
• OSS-Fuzz check_build passed for all 12 targets.
• Every packaged seed corpus was replayed with its matching dictionary (12/12 passed).