Upgrade to Go 1.25

[Starosdev]

Summary

Upgrade the project from Go 1.24.6 to Go 1.25.0 to take advantage of new features and continued security support.

Why

• Container-aware GOMAXPROCS: Go 1.25 auto-tunes GOMAXPROCS based on cgroup CPU limits (Scrutiny runs in Docker)
• Faster JSON decoding: New encoding/json implementation benefits SMART data ingestion API
• Smaller binaries: DWARF 5 debug info reduces binary size and link time across 10-platform build matrix
• Unlocks shoutrrr v0.12.0: Latest fork version requires Go 1.25.3 (currently pinned to v0.8.17)
• Security: Go 1.24 stops receiving patches when Go 1.26 ships (~Feb 2026)

Acceptance Criteria

• go.mod updated to go 1.25.0 with toolchain go1.25.6
• CI workflows updated (ci.yaml, release.yaml, sonarqube.yaml)
• All Dockerfiles updated to golang:1.25-trixie
• All existing tests pass
• Docker image builds and deploys successfully

Additional Context

• golang:1.25-trixie is available on Docker Hub
• ghcr.io/packagrio/packagr:latest-golang has Go 1.24.4; set GOTOOLCHAIN=auto for compatibility
• macOS 12 minimum (Go 1.25 drops macOS 11) - CI uses macos-latest so no impact
• Depends on Switch to maintained shoutrrr fork (v0.8.17) #207 (shoutrrr fork migration) being merged first