feat: Add Grafana auto-update & improve classifier

Add auto-update for Grafana on Synology via SSH + docker compose,
with review examples and a context.txt describing the specific setup
(Prometheus + Node Exporter, no plugins) so the classifier can
ignore plugin-only breaking changes.

The classifier now loads an optional context.txt per service to
tailor decisions to the actual deployment. It also truncates large
release notes intelligently, keeping important sections (breaking
changes, deprecations, migration notes) while dropping long PR
lists that add no signal.

test_classifier.py now also loads context.txt and accepts any
service name as argument.

services/grafana/review-examples/auto-1.txt

@@ -0,0 +1,25 @@
+action: auto
+reason: Patch release with security fixes, minor enhancements, and bug fixes. No breaking changes or manual steps required.
+---
+[Download page](https://grafana.com/grafana/download/12.4.2)
+[What's new highlights](https://grafana.com/docs/grafana/latest/whatsnew/)
+
+### Features and enhancements
+
+- **Analytics tab:** Improve voice over accessibility (Enterprise)
+- **Dashboards a11y:** Do not open time zonemenu on focus
+- **Dashboards:** Resolve display names by identity in version history
+- **Plugins:** Forward AWS SDK credential chain env vars to external AWS plugins
+- **Public Dashboards:** Prevent unintended CRUD operations from different orgs
+
+### Bug fixes
+
+- **IAM:** Handle NULL team_member.external column to fix dashboard loading
+- **Plugins:** Fix installer IsDisabled condition
+- **Plugins:** Forward PLUGIN_UNIX_SOCKET_DIR to plugin processes to fix tmp dir in restricted environments
+- **Security:** Fixes CVE-2026-27876
+- **Security:** Fixes CVE-2026-27877
+- **Security:** Fixes CVE-2026-28375
+- **Security:** Fixes CVE-2026-27879
+- **Security:** Fixes CVE-2026-27880
+- **Security:** Fixes CVE-2026-33375