upgrade deps, kube 3.x, edition 2024, ghcr publishing

[wseaton]

Summary

• Upgrade kube-rs 0.92 -> 3.1, k8s-openapi 0.22 -> 0.27, schemars 0.8 -> 1.2
• Upgrade OpenTelemetry stack 0.26 -> 0.31 (full pipeline rewrite for new builder API)
• Upgrade thiserror 1 -> 2, secrecy 0.8 -> 0.10, ldap3 0.11 -> 0.12
• Rust edition 2021 -> 2024, MSRV 1.83 -> 1.88, version bump to 0.4.0
• Replace chrono with jiff for k8s timestamp handling (k8s-openapi 0.27 requirement)
• Replace once_cell with std::sync::LazyLock
• Remove deprecated serde_yaml dependency
• Use scale subresource API (patch_scale) instead of patching spec.replicas directly
• Regenerate CRDs from upstream YAML via kopium with JsonSchema derives (schemars 1.x)
• Add GitHub Actions workflow for GHCR image publishing on tag push
• Update README, justfile, deployment manifest to point to ghcr.io

Test plan

• cargo fmt clean
• cargo clippy --all --all-features clean
• cargo test --all --all-features passes
• Compiles with default features and with otel feature
• CI workflow builds images successfully (verify after merge/tag)
• Integration test against a cluster (follow-up)

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