Extension server linux_arm64 directory contains x86-64 binaries instead of ARM64

[sparkling]

Bug Description

The extension server image (ghcr.io/predictable-labs/extension-repo:latest) contains incorrectly packaged binaries in the linux_arm64 directory. The files are x86-64 (AMD64) ELF binaries, not ARM64.

This causes LOAD algo to fail on ARM64 Linux systems (including k3d/Docker on Apple Silicon Macs).

Steps to Reproduce

1. Run an ARM64 Linux container with Ryugraph
2. Install and load the algo extension:

import ryugraph
db = ryugraph.Database('/data/test')
conn = ryugraph.Connection(db)
conn.execute("INSTALL algo FROM 'http://extension-server:80/'")  # Downloads file
conn.execute("LOAD algo")  # FAILS

Error Message

RuntimeError: IO exception: Failed to load library:
/home/user/.ryu/extension/25.9.0/linux_arm64/algo/libalgo.ryu_extension
Error: cannot open shared object file: No such file or directory.

The file exists (453,888 bytes) but cannot be loaded because it's the wrong architecture.

Root Cause Verification

Inspected the ELF header of the downloaded extension:

head -c 20 libalgo.ryu_extension | xxd

00000000: 7f45 4c46 0201 0103 0000 0000 0000 0000  .ELF............
00000010: 0300 3e00                                ..>.

• 7f45 4c46 = ELF magic number (correct)
• 0300 3e00 at position 18 = machine type 0x003e = x86-64 (AMD64)
• ARM64 should be 0xb7 (183)

Extension Server Contents

Verified inside the extension server container:

/usr/share/nginx/html/v25.9.0/
├── linux_amd64/algo/libalgo.ryu_extension  # x86-64 binary ✓
├── linux_arm64/algo/libalgo.ryu_extension  # x86-64 binary ✗ (should be ARM64)
├── osx_amd64/algo/libalgo.ryu_extension
├── osx_arm64/algo/libalgo.ryu_extension
└── win_amd64/algo/libalgo.ryu_extension

Environment

• Ryugraph version: 25.9.2
• Extension server: ghcr.io/predictable-labs/extension-repo:latest
• Host: Apple Silicon Mac (M1/M2/M3)
• Container runtime: k3d with OrbStack / Docker Desktop
• Container arch: linux/arm64

Workaround

Build and run all containers as linux/amd64. On Apple Silicon, these run via Rosetta 2 emulation, which works but is slower than native ARM64.

Expected Behavior

The linux_arm64 directory should contain actual ARM64 (aarch64) ELF binaries that can be loaded by ARM64 Linux processes.