Merge curation-v2-step3 into curation-v2 (steps 2 and 3 united)

Union merge of the Claude editor (step 2) and the embeddings/signals/telemetry
work (step 3): both config trees, per-provider LLM budgets plus the Voyage
meter, one startup provider log, runs.config_json with ranking and voyage
settings, and selected picks' why lines landing in candidate_runs.editor_why.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A1rCLQeKBgnBo3oTgHuTMe

src/curate/mod.rs

@@ -11,11 +11,14 @@
 //! client; selection and editorial on the editor with per-call bulk fallback.
 
 pub mod editorial;
+pub mod embedding;
 pub mod llm;
 pub mod prefilter;
 pub mod profile;
 pub mod score;
 pub mod select;
+pub mod signals;
+pub mod telemetry;
 
 use jiff::civil::Date;