Dockerfile: bundle the vlan and tuning CNI plugins - #760

Is this a BUG FIX or a FEATURE ?:

/kind feature

What this PR does / why we need it:

CNIDevice accepts CNI configurations, but the controller image does not contain vlan or tuning. A configuration requesting either plugin therefore fails plugin lookup unless users supply external binaries or rebuild the image.

The existing CNI builder already compiles both plugins. Copy them into /opt/openperouter/cni/bin/ alongside the existing plugins and document the available bundle. This enables tagged VLAN underlays using the existing IPAM plugins and chained interface tuning, such as MTU changes.

Special notes for your reviewer:

• This is two additional Dockerfile COPY instructions plus the configuration reference update. The upstream CNI repository and pinned revision are unchanged.
• VLAN still requires IPAM at the pinned revision. Optional IPAM is proposed independently in vlan: make IPAM optional for L2-only interfaces containernetworking/plugins#1302; this PR does not depend on that change or a personal fork.
• Built the complete image locally on Linux amd64 with docker build -t local/openperouter:bundle-vlan-tuning-review ..
• Both bundled binaries successfully handle CNI_COMMAND=VERSION inside the resulting image.
• A smoke test in an isolated container and child network namespace verified VLAN ID 123, static IPAM address assignment, a chained tuning ADD setting MTU 1400, and tuning/VLAN DEL cleanup.
• git diff --check passes. No live-cluster end-to-end test or local arm64 build was run.

Release note:

The controller image now includes the vlan and tuning CNI plugins for tagged underlay interfaces and chained interface configuration.

AI Guidelines Acknowledgment:

• I have reviewed all changes in this PR, including any AI-generated content, and I take full responsibility for its accuracy and correctness.