fix: use target-specific Debian arch names in Cross.toml

[mostronatorcoder]

Summary

Fixes the Debian architecture mapping issue in Cross.toml that caused 4 out of 5 cross-compilation targets to fail in v0.1.2 release.

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Problem

Release workflow v0.1.2 failed: https://github.com/MostroP2P/mostrix/actions/runs/23092917539

Failed targets:

• armv7-unknown-linux-gnueabi → E: Unable to locate package libssl-dev:armel
• aarch64-unknown-linux-musl → package not found
• x86_64-unknown-linux-musl → package not found
• x86_64-unknown-freebsd → package not found

Only succeeded:

• x86_64-pc-windows-gnu (by accident, uses different OpenSSL linking)

Root cause: Generic [build] section used $CROSS_DEB_ARCH variable which doesn't map correctly to Debian multi-arch package names for all Rust targets.

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Solution

Replace generic configuration with target-specific sections using correct Debian architecture names:

# Before (broken):
[build]
pre-build = [
    "dpkg --add-architecture $CROSS_DEB_ARCH",  # ❌ Wrong for most targets
    "apt-get update",
    "apt-get install -y libssl-dev:$CROSS_DEB_ARCH pkg-config"
]

# After (fixed):
[target.armv7-unknown-linux-gnueabi]
pre-build = [
    "dpkg --add-architecture armhf",  # ✅ Correct Debian arch
    "apt-get update",
    "apt-get install -y libssl-dev:armhf pkg-config"
]
# ... + 4 more target-specific configs

Rust Target → Debian Arch Mapping

Rust Target	Debian Arch	Notes
x86_64-unknown-linux-musl	amd64	Standard x86_64
aarch64-unknown-linux-musl	arm64	ARM 64-bit
armv7-unknown-linux-gnueabi	armhf	Hard-float ABI (not armel)
x86_64-pc-windows-gnu	N/A	No multi-arch, use native packages
x86_64-unknown-freebsd	N/A	No multi-arch, use native packages

Key insight: ARMv7 gnueabi suffix doesn't mean soft-float (armel) — it uses hard-float (armhf). This is a common cross-compilation gotcha.

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Validation

• cargo fmt — no changes
• cargo clippy --all-targets --all-features -- -D warnings — passes
• cargo test — passes

Next step: After merge, re-trigger v0.1.2 release tag to verify all 5 targets build successfully.

---

References

• Debian multi-arch guide: https://wiki.debian.org/Multiarch/HOWTO
• Cross target-specific config: https://github.com/cross-rs/cross/wiki/Configuration#target
• ARMv7 ABI confusion: https://wiki.debian.org/ArmHardFloatPort
• Similar pattern in cargo-chef: uses explicit target configs for OpenSSL