fix: add Cross.toml to fix OpenSSL cross-compilation failures

[mostronatorcoder]

Summary

Fixes the OpenSSL cross-compilation failures that caused the v0.1.1 release workflow to fail on all target architectures.

---

Problem

Release workflow run failed: https://github.com/MostroP2P/mostrix/actions/runs/23092367046

All 5 cross-compilation targets failed with:

error: failed to run custom build command for `openssl-sys v0.9.111`
Could not find directory of OpenSSL installation

Root cause: reqwest uses native-tls feature → depends on openssl-sys → needs OpenSSL dev headers for target architecture → cross-compilation containers don't include these by default.

---

Solution

Add Cross.toml configuration file with pre-build hook:

[build]
pre-build = [
    "dpkg --add-architecture $CROSS_DEB_ARCH",
    "apt-get update",
    "apt-get install -y libssl-dev:$CROSS_DEB_ARCH pkg-config"
]

This installs OpenSSL development headers for the target architecture before compilation, allowing openssl-sys build script to locate them.

---

Validation

• cargo fmt — no changes
• cargo clippy --all-targets --all-features -- -D warnings — passes
• cargo test — 10 passed, 0 failed

Next step: After merge, re-trigger release workflow to verify cross-compilation succeeds.

---

Alternative Considered

Switch to rustls-tls:

reqwest = { version = "0.13.2", default-features = false, features = ["rustls-tls", "json", "http2"] }

Pros:

• No OpenSSL dependency
• Pure Rust TLS stack
• Easier cross-compilation

Cons:

• Changes TLS behavior (different certificate validation, cipher suites)
• Requires thorough testing of HTTPS connections
• May break compatibility with some servers
• Larger binary size (rustls is bigger than linking to system OpenSSL)

Decision: Use Cross.toml fix for now (minimal risk). Consider rustls-tls migration in a future PR with proper testing.

---

References

• Cross configuration docs: https://github.com/cross-rs/cross/wiki/Configuration
• Similar pattern used in: cargo-chef, diesel_cli, tokio-postgres
• OpenSSL cross-compilation guide: https://docs.rs/openssl/latest/openssl/#automatic

Summary by CodeRabbit

Release Notes

• Chores
  • Enhanced build infrastructure to support cross-compilation across multiple target architectures, ensuring proper dependency resolution during compilation.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: afc72c22-8662-43de-9268-b5d66625e17b

📥 Commits

Reviewing files that changed from the base of the PR and between 532af65 and cfae28e.

📒 Files selected for processing (1)

• Cross.toml

---

Walkthrough

Adds a Cross.toml configuration file to enable cross-compilation targeting multiple architectures. The configuration includes a pre-build hook that prepares the build environment by adding Debian architectures, updating package lists, and installing OpenSSL development libraries and pkg-config.

Changes

Cohort / File(s)	Summary
Cross-Compilation Configuration Cross.toml	Introduces build configuration with pre-build hook that executes shell commands to install libssl-dev and pkg-config for target architecture support during cross-compilation.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• feat: add automated multi-arch release workflow #32: Adds GitHub Actions workflow that uses the cross tool to build multi-architecture artifacts, complementing this Cross.toml configuration setup.

Poem

🐰 Across the architectures we hop,
With Cross.toml, we'll never stop!
OpenSSL libraries, all in place,
Building swift for every space. 🏗️

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/cross-compilation-openssl

📝 Coding Plan

• Generate coding plan for human review comments

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