feat(M2): CAM++ embedder + Embedder trait for v1.0

CHANGELOG.md

@@ -39,6 +39,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New manifest entry `[models.powerset_fp32]` for sherpa-onnx-pyannote-segmentation-3-0.
   Profiles still resolve to the legacy `silero_vad` segmenter; M6 swaps them.
 
+### Added (M2 — Embedder trait + CAM++)
+- `polyvoice::embedder` module: `Embedder` trait, `EmbedderError`, `EmbedderPool`,
+  `apply_overlap_mask` helper.
+- `CamPlusPlusExtractor` (192-d output, gated `onnx`+`embedder`) — wraps the
+  same fbank pipeline as ResNet34 with the CAM++ ONNX model.
+- `ResNet34Adapter` — bridges existing `FbankOnnxExtractor` (256-d, WeSpeaker)
+  to the new `Embedder` trait. Legacy `EmbeddingExtractor` trait is unchanged.
+- New Cargo feature `embedder` (in default features). Pure-Rust core (trait,
+  `apply_overlap_mask`, `EmbedderPool` over a generic `E: Embedder`) is
+  wasm32-clean; `CamPlusPlusExtractor` and `ResNet34Adapter` additionally
+  require `onnx`.
+- New manifest entry `[models.cam_pp_fp32]`. Profiles still resolve to
+  `wespeaker_resnet34` until M6 swaps them.
+
 ## [0.5.2] - 2025-05-05
 
 ### Added

Cargo.toml

@@ -12,7 +12,7 @@ categories = ["multimedia::audio", "science"]
 crate-type = ["cdylib", "rlib"]
 
 [features]
-default = ["spectral", "segmentation"]
+default = ["spectral", "segmentation", "embedder"]
 # ONNX-based embedding extractors (pulls ort).
 onnx = ["dep:ort"]
 # C FFI bindings.
@@ -35,6 +35,12 @@ spectral = ["dep:faer"]
 # wasm32-clean. The ONNX-backed `PowersetSegmenter` additionally requires `onnx`.
 segmentation = []
 
+# v1.0 Embedder trait + CAM++/ResNet34 adapters + EmbedderPool + overlap masking.
+# The pure-Rust algorithmic core (trait, overlap mask, pool with mock backend)
+# compiles to wasm32-clean. The ONNX-backed `CamPlusPlusExtractor` and
+# `ResNet34Adapter` additionally require `onnx`.
+embedder = []
+
 # Model profile bundles. M0 only emits metadata; CLI uses these to pick which
 # manifest entries to ensure(). M5 will introduce INT8 model variants.
 profile-mobile = []