docs: expand Chord-Unicode reference with Greek alphabet and math sections
Add Greek Alphabet table (full A–Ω), Number Sets (ℝ ℕ ℤ ℚ ℂ ℵ),
Calculus/Analysis, Set Theory, Logic, Geometry, and Floor & Ceiling
sections to match the new chord table entries. Move pi and micro out
of Math & Science into their respective sections; add equiv and prop.
Disambiguation notes added for mu, sub, and sup.
docs: replace non-ASCII characters with ASCII equivalents to suppress Gitea warnings
Replace all ambiguous Unicode characters in wiki pages with ASCII
equivalents (box-drawing -> +/-/|, arrows -> ^/v/</->, em-dashes -> --,
special symbols -> ASCII approximations). Add a note to Chord-Unicode.md
explaining that its Unicode content is intentional.
rootiest
