queelius/charpx: v0.5.1: Code Quality Pass

Code-review fixes Thickness fix in vizlib charts. sparkline() and line_plot() now paint a true NxN brush at any thickness. Previously even thickness values silently rounded up to the next odd (thickness=2 looked like thickness=3, thickness=4 looked like 5). Thickness and series plumbed through wrappers. dapple.charts.sparkline() accepts thickness=; dapple.charts.line_plot() accepts thickness= and series=. Both previously required dropping to the pixel-level dapple.extras.vizlib.charts API. New public API dapple.warm_glyph_cache(glyph_set, cell_width=8, cell_height=16, font_path=None) pre-builds the fingerprint glyph cache and returns the count of glyphs successfully rendered. Useful before benchmarking; the returned count is lower than requested if the active font lacks coverage for some glyphs. dapple.clear_glyph_caches() drops cached glyph bitmaps for benchmarking cold-cache builds or for memory reclamation after rendering with large custom glyph sets. Cleanup Removed the diffcat and storycat extras (source, tests, docs, demo script). Moved exploratory scripts mega_fingerprint.py and compare_renderers.py out of the repo root into examples/. Added docs/concepts/fingerprint-acceleration.md documenting the BLAS-accelerated glyph matching used by the fingerprint renderer. Tests 930 passed, 5 skipped. New: TestLineThickness regression suite (3 tests) and a _TOOL_SECTIONS / _EXTRAS consistency check in test_skill.py.