spike(rust/scaffold): create spike/audio-sync Cargo binary crate

.gitignore

@@ -108,3 +108,6 @@ scripts/diarize/__pycache__/
 
 # Editor
 .vscode/settings.json
+
+# Rust spike build artifacts
+spike/audio-sync/target/

docs/implementation-guides/issue-95-rust-scaffold.md

@@ -0,0 +1,49 @@
+# Issue #95 — spike(rust/scaffold): create spike/audio-sync Cargo binary crate
+
+## Goal
+
+Create a minimal, buildable Cargo binary crate at `spike/audio-sync/` as a clean skeleton for subsequent Rust spike issues (#96, #97, #98). No algorithm logic — stubs only.
+
+## Steps
+
+### Step 1 — Create Cargo.toml
+
+Create `spike/audio-sync/Cargo.toml` as a standalone manifest (no workspace).
+
+**Status check:** `test -f spike/audio-sync/Cargo.toml`
+
+### Step 2 — Create src/main.rs and src/lib.rs stubs
+
+Create `spike/audio-sync/src/main.rs` with stub `main()` and `spike/audio-sync/src/lib.rs` as an empty file.
+
+**Status check:** `test -f spike/audio-sync/src/main.rs && test -f spike/audio-sync/src/lib.rs`
+
+### Step 3 — Add spike/audio-sync/target/ to .gitignore
+
+Append `spike/audio-sync/target/` to the root `.gitignore` so build artifacts are not tracked.
+
+**Status check:** `grep -q 'spike/audio-sync/target/' .gitignore`
+
+### Step 4 — Add spike/audio-sync/README.md
+
+Create setup and usage instructions for peers who need to install Rust.
+
+**Status check:** `test -f spike/audio-sync/README.md`
+
+### Step 5 — Verify build
+
+Run `cargo build --manifest-path spike/audio-sync/Cargo.toml` and confirm exit 0.
+
+**Status check:** `cargo build --manifest-path spike/audio-sync/Cargo.toml && echo OK`
+
+### Step 6 — Commit
+
+Commit `Cargo.toml`, `Cargo.lock`, `src/main.rs`, `src/lib.rs`, `README.md`, and `.gitignore` change.
+
+**Status check:** `git log --oneline -1 | grep -q 'spike(rust/scaffold)'`
+
+## Out of scope
+
+- Any algorithm logic
+- Root-level `Cargo.toml` workspace
+- CI configuration

spike/audio-sync/Cargo.toml

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+[package]
+name = "audio-sync"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rustfft = "6"
+hound = "3"

spike/audio-sync/README.md

@@ -0,0 +1,61 @@
+# audio-sync spike
+
+Standalone Rust binary for FFT cross-correlation sync. Part of the RFC 0001 Rust rewrite spike (see [issue #93](https://github.com/ragTechDev/deckcreate/issues/93)).
+
+> **Temporary** — this crate lives under `spike/` and will be deleted when the spike concludes.
+
+## Prerequisites
+
+Rust stable toolchain via `rustup`:
+
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+```
+
+Then restart your shell (or run `source "$HOME/.cargo/env"`), and verify:
+
+```bash
+rustc --version   # e.g. rustc 1.79.0
+cargo --version
+```
+
+No other dependencies — `rustfft` and `hound` are pure Rust and compile without any system libraries.
+
+## Build
+
+From the repo root:
+
+```bash
+cargo build --manifest-path spike/audio-sync/Cargo.toml
+```
+
+Or from inside the crate:
+
+```bash
+cd spike/audio-sync
+cargo build
+```
+
+## Run
+
+```bash
+cargo run --manifest-path spike/audio-sync/Cargo.toml
+# → audio-sync spike — not yet implemented
+```
+
+## Dependencies
+
+| Crate | Version | Purpose |
+|-------|---------|---------|
+| `rustfft` | 6 | Pure-Rust FFT (no native deps, deterministic across platforms) |
+| `hound` | 3 | WAV file reader/writer |
+
+## Fixtures
+
+Test WAV files are in `fixtures/`:
+
+| File | Description |
+|------|-------------|
+| `fixtures/audio-track.wav` | Isolated audio track |
+| `fixtures/video-audio.wav` | Audio extracted from video |
+| `fixtures/baseline.json` | JS baseline offset for cross-validation |

spike/audio-sync/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("audio-sync spike — not yet implemented");
+}