maint: prepare for release v2.9.5 (#1542)

## Which problem is this PR solving?

- prepare for 2.9.5 release

## Short description of the changes

- update CHANGELOG.md and RELEASE_NOTES.md

Author: VinozzZ

CHANGELOG.md

@@ -1,5 +1,32 @@
 # Refinery Changelog
 
+## 2.9.5 2025-04-24
+
+This release brings a experimental feature for OpAMP. This feature is intended for internal use only and is not supported or recommended for production.
+
+### Features
+
+- feat: add experimental support for opamp (#1528) | [Alex Boten](https://github.com/AlexBoten)
+- feat: Support arbitrary envvar replacement in config strings (#1517) | [Kent Quirk](https://github.com/KentQuirk)
+
+### Fixes
+
+- fix: improve trace cache doc and metric (#1535) | [Yingrong Zhao](https://github.com/vinozzz)
+- fix: flush internal metrics on shutdown (#1534) | [Yingrong Zhao](https://github.com/vinozzz)
+- fix: add env var support for APIHost in telemetry cfg (#1536) | [Yingrong Zhao](https://github.com/vinozzz)
+- fix: ensure SendKeyMode priority (#1527) | [Alex Boten](https://github.com/AlexBoten)
+- fix: update trace_id field to meta.trace_id (#1520) | [Alex Boten](https://github.com/AlexBoten)
+
+### Maintenance
+
+- docs: some copyedits from docs (#1526) | [Jamie Danielson](https://github.com/JamieDanielson)
+- docs: add missing metrics and extra details (#1515) | [Jamie Danielson](https://github.com/JamieDanielson)
+- maint: Mark TraceLocalityMode as experimetnal (#1522) | [Mike Goldsmith](https://github.com/MikeGoldsmith)
+- maint(deps): bump the minor-patch group with 15 updates (#1518) | [dependabot[bot]](https://github.com/dependabot[bot])
+- maint: record sampler key cardinality as metric (#1537) | [Yingrong Zhao](https://github.com/vinozzz)
+- maint(deps): bump github.com/golang/snappy from 0.0.4 to 1.0.0 (#1519) | [dependabot[bot]](https://github.com/dependabot[bot])
+- maint(deps): bump golang.org/x/net from 0.37.0 to 0.38.0 (#1529) | [dependabot[bot]](https://github.com/dependabot[bot])
+
 ## 2.9.4 2025-03-25
 
 ### Features

RELEASE_NOTES.md

@@ -2,6 +2,10 @@
 
 While [CHANGELOG.md](./CHANGELOG.md) contains detailed documentation and links to all the source code changes in a given release, this document is intended to be aimed at a more comprehensible version of the contents of the release from the point of view of users of Refinery.
 
+## Version 2.9.5
+
+This release includes improvements to trace cache documentation, internal metric flushing on shutdown, and enhanced metric visibility such as sampler key cardinality. It also introduces environment variable substitution in config strings and experimental support for OpAMP. The OpAMP feature is intended for *internal use only* and is *not supported or recommended* for production.
+
 ## Version 2.9.4
 
 This is a maintenance release that adds the `incoming_router_event_bytes` and `peer_router_event_bytes` metrics, which use a histogram to record the number of bytes per received event.