Uppercase operator glyphs, more effects, drop embedded spectrum

- Operators are now UPPERCASE (orca-style): O A U V N sources, L H B SVF
  filters (with resonance), E G R envelope/gain/ringmod, S C F D shapers
  (soft/clip/fold/decimate), M mix, ! out. Digits = constants, lowercase = CC.
- TUI rewritten on crossterm reusing orca-rs's grid-view approach (centered
  canvas, per-glyph colour); the spectrum is gone - run spectrust on the side.
- Drops the ratatui and rustfft deps.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GLUwWE2KmFPzhKaf67tWbx

Cargo.toml

@@ -13,7 +13,6 @@ codegen-units = 1
 anyhow = "1"
 pipewire = "0.10"
 midir = "0.10"
-rustfft = "6.2"
 arc-swap = "1.7"
 rtrb = "0.3"
-ratatui = "0.29"
+crossterm = "0.29"