docs(network): Drop references to filter_from_cube XDP program

[chenhengqi]

The filter_from_cube XDP program was removed in our open source release. Sync networking docs with the current implementation.

[github-actions]

Claude finished @chenhengqi's task in 4m 30s —— View job

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PR Review: docs(network): Drop references to filter_from_cube XDP program

• Gather context and read changed files
• Check DCO compliance
• Review code quality and provide feedback
• Post inline comments for specific issues

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DCO Check

The commit 79beaec includes Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com> -- DCO compliance is satisfied.

Summary

This PR cleanly removes all references to the filter_from_cube XDP program from three documentation files:

• CubeNet/cubevs/API.md -- Removes the filter_from_cube row from the BPF programs table and updates line numbers
• docs/architecture/network.md -- Removes the XDP paragraph, Init() XDP reference, step 4 in Init flow, and updates the mermaid diagram
• docs/zh/architecture/network.md -- Consistent Chinese translation of the same changes

The English and Chinese docs are kept in sync, and the mermaid diagrams are consistently updated. The removals are thorough -- no stale filter_from_cube or XDP references remain.

Issue Found

BPF Map line numbers in API.md are now stale. The PR correctly updated the program line numbers (73-76 -> 78-80) to match the current source, but the BPF Map table above it still references lines 78-81, which now conflict with the program line numbers. Per the current cubevs.go, the map constants have shifted to lines 82-85. See the inline comment for details.

[github-actions]

The program line numbers (78, 79, 80) now overlap with the BPF Map table above, which lists ifindex_to_mvmmeta at cubevs.go:78 and mvmip_to_ifindex at cubevs.go:79.

Checking the current source (CubeNet/cubevs/cubevs.go), the program names are correctly at lines 78-80, but the map names have shifted to lines 82-85:

78: programNameFromEnvoy = "from_envoy"
79: programNameFromCube  = "from_cube"
80: programNameFromWorld = "from_world"
81: // MapNameIfindexToMVMMetadata and the following are maps created by CubeVS.
82: MapNameIfindexToMVMMetadata = "ifindex_to_mvmmeta"
83: MapNameMVMIPToIfindex       = "mvmip_to_ifindex"
84: MapNameRemotePortMapping    = "remote_port_mapping"
85: MapNameLocalPortMapping     = "local_port_mapping"

The BPF Map table (lines 82-85 in this file) should also be updated to reflect the new line numbers (82-85) instead of the current 78-81.