v7: standalone Sing Detect app — full Tauri project tree

Promotes the v6 detection slice into a complete, buildable Tauri 2 app and
renames Stream Studio → Sing Detect (detection-only; video-concat split to its
own project). Proper src/ + src-tauri/ layout, Python sidecar under sidecar/,
app icons, package/Cargo manifests, and dev/build/pack scripts.

Pipeline unchanged in spirit: Rust drives ffmpeg to a 16 kHz mono WAV, the
Python sidecar (inaSpeechSegmenter) emits line-JSON segments, and Rust writes
EDL / markers CSV / CSV / JSON exports. Long ops run on spawn_blocking; cancel
kills the whole py -3.10 process tree.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sidecar/requirements.txt

@@ -0,0 +1,12 @@
+# Stream Studio detection sidecar — install into a Python 3.10 environment.
+#   py -3.10 -m pip install -r requirements.txt
+#
+# TensorFlow does NOT support Python 3.12+, which is why the sidecar pins 3.10
+# even though the rest of the toolchain can use newer Python.
+
+# NumPy MUST stay <2: TensorFlow 2.11 is built against NumPy 1.x and crashes on
+# NumPy 2.x with "_pywrap_bfloat16.TF_bfloat16_type() () -> handle". Keep this pin
+# above tensorflow so the resolver installs the compatible NumPy.
+numpy<2
+inaSpeechSegmenter
+tensorflow            # use: tensorflow[and-cuda] for NVIDIA GPU acceleration