CryptoMiniSat release/v5.14.6

CryptoMiniSat 5.14.6

This is a maintenance release with build fixes, internal refactoring, and improved simplification statistics.

Build & packaging fixes

• Fix BreakID build (#826)
• Fix zlib download by fetching from the GitHub release instead of zlib.net, which was failing
• Updated Nix flake inputs

Statistics & internals

• Wrap OccSimplifier::finish_up and add a depth field to [simp-stats]
• Wrap backbone_simpl with [simp-stats] and fix the occurrence-based irred_long_cls count

Cleanup

• Broad refactoring for clarity across the clause allocator, SCC finder, var replacer, and related code (#818)
• Add a CryptoMiniSat skill file (SKILL.md)
• README updates

Full changelog: release/v5.14.5...release/v5.14.6

What's Changed

• Fix BreakID build by @msoos in #826
• Refactoring things by @msoos in #818

Full Changelog: release/v5.14.5...release/v5.14.6