Provider-agnostic LLM registry, config check, migration runbook

[llm] assigns the bulk and editor roles by name over a [providers.*]
registry (kind = openai | anthropic, per-provider model, effort, daily
ceiling and price table); DeepseekBackend becomes OpenAiCompatibleBackend
(reasoning_effort passthrough), AnthropicBackend builds from the same
ProviderConfig, meters and provider_costs are keyed by provider name.
Gemini 3.8 Flash is declared via Google's OpenAI-compatible endpoint so
switching the editor is one line (or DAILY_EPUB_LLM__EDITOR=gemini for an
A/B dry run). Stale [deepseek]/[anthropic] tables, the top-level
max_daily_usd and the old key env vars fail loudly.

daily-epub config check validates and prints the resolved roles, models,
key presence and paths without opening the database.

docs/runbooks/curation-v2-migration.md walks the server upgrade from v1.

Registry implemented by a Claude agent from an orchestrator brief;
verified fmt/clippy(-W dead_code)/test green.

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

src/world.rs

@@ -718,11 +718,14 @@ mod tests {
         backend: std::sync::Arc<crate::curate::llm::MockBackend>,
         limit: f64,
     ) -> LlmClient {
-        let config = crate::config::DeepseekConfig::default();
+        let config = crate::config::ProviderConfig::deepseek();
         LlmClient::with_backend(
             "mock",
             "World Briefing test".into(),
-            crate::curate::llm::UsageMeter::new(&config, limit),
+            crate::curate::llm::UsageMeter::with_prices(
+                crate::curate::llm::PriceTable::from(&config),
+                limit,
+            ),
             backend,
         )
     }