v0.6.0 - RQ1: BGE embedding default

Promote bge-base-en-v1.5 to the default embedding profile, keep MiniLM profiles selectable, and add an opt-in Qwen3 embedding profile using the live onnx-community q8 export.

Add profile-specific pooling, query prefixes, token limits, streaming asset downloads, and health/setup disclosure. Recall and feedback now use query embeddings while store/backfill paths keep passage embeddings.

Validation: CARGO_TARGET_DIR=target-codex-rq1 rtk cargo check --manifest-path daemon-rs/Cargo.toml --tests; rtk cargo test --manifest-path daemon-rs/Cargo.toml embeddings -- --nocapture; rtk cargo clippy --manifest-path daemon-rs/Cargo.toml --tests -- -D warnings; rtk cargo test --manifest-path daemon-rs/Cargo.toml (473 passed).

Author: AdityaVG13