refactor(config): migration 17-to-18 to unify Provider/Reprovider into Provide.DHT (#10951)

* refactor: consolidate Provider/Reprovider into unified Provide config

- merge Provider and Reprovider configs into single Provide section
- add fs-repo-17-to-18 migration for config consolidation
- improve migration ergonomics with common package utilities
- convert deprecated "flat" strategy to "all" during migration
- improve Provide docs

* docs: add total_provide_count metric guidance

- document how to monitor provide success rates via prometheus metrics
- add performance comparison section to changelog
- explain how to evaluate sweep vs legacy provider effectiveness

* fix: add OpenTelemetry meter provider for metrics

- set up meter provider with Prometheus exporter in daemon
- enables metrics from external libs like go-libp2p-kad-dht
- fixes missing total_provide_count_total when SweepEnabled=true
- update docs to reflect actual metric names

---------

Co-authored-by: gammazero <11790789+gammazero@users.noreply.github.com>
Co-authored-by: guillaumemichel <guillaume@michel.id>
Co-authored-by: Daniel Norman <1992255+2color@users.noreply.github.com>
Co-authored-by: Hector Sanjuan <code@hector.link>

core/coreapi/coreapi.go

@@ -70,7 +70,7 @@ type CoreAPI struct {
 	unixFSPathResolver pathresolver.Resolver
 
 	provider          node.DHTProvider
-	providingStrategy config.ReproviderStrategy
+	providingStrategy config.ProvideStrategy
 
 	pubSub *pubsub.PubSub