Port Rust patch script catalog

docs/migration-checklist.md

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+# Migration Checklist
+
+This repo is now the authoring-side home for Aquarium Synth patch scripts and
+Faust generation. The Rust crate remains useful as a reference lab, but the
+current C# surface should not depend on somebody remembering what got built
+there.
+
+## Ported
+
+- Patch graph model: voices, envelopes, pitch motion, duty motion, filters,
+  phasers, arpeggios, FM, color shaping, formants, repeat, and control lanes.
+- Patch script parser: `patch`, `default`, `def`, `voice`, `mod`/`bus`, and
+  `lfo`/`control`.
+- Rust DSL shorthand aliases used by the golfed scripts, including `p`, `d`,
+  `v`, `u`, `w`, `f`, `g`, `s`, `pr`, `pdr`, `du`, `dur`, `l`, `h`, `drv`,
+  `fl`, `fmix`, `fmi`, `mods`, and `m`.
+- Modulation routing in both direct style (`mod n=wob g=.4 l=.5`) and routed
+  style (`bus n=sway to=g:.1,l:-.2,fmix:.3`).
+- Built-in script catalog for classic SFXR, classic 808, FM bell, and wobble
+  bass primitive golf scripts.
+- Abstract SFXR golf script using defaults and templates.
+- Faust source emitter and installed-compiler wrapper for C, C++, C#, and Rust
+  target code generation.
+- Tests that parse/export all built-in primitive scripts and validate Faust
+  source when Faust is installed.
+
+## Still Deliberate
+
+- The C# repo does not yet include an audio renderer, analysis metric suite, or
+  exhaustive Rust-vs-Faust audio parity harness. Faust is the renderer target,
+  so C# should own authoring and validation first.
+- SFXR preset atoms such as `sfxr preset=laser mutate_seed=...` are not carried
+  over yet. The current migration preserves the primitive patch construction
+  path, which is the part we want in the engine.
+- Random mutation, parameter-space search, and readability/code-golf scoring are
+  still Rust-reference features until we decide which ones belong in C# tools
+  versus offline authoring utilities.
+
+## Next Pull
+
+- Add JSON serialization contracts for `SynthPatch` once the Vortice-side load
+  boundary is known.
+- Add a Faust compilation cache keyed by script/options/source hash.
+- Add a small CLI so build scripts can compile `.aqs` patch files into Faust or
+  generated C# without writing host code first.