fix(ci): install zig for all cross-compilation targets

Fixes missing zig dependency that blocks all non-macOS builds:

- Add Cross.toml with pre-build commands to install zig in cross containers
  for aarch64, x86_64, and armv7 musl Linux targets
- Add Windows zig installation via chocolatey in release workflow
- Fix Docker workspace issue by creating infrastructure directory
- Update Cargo.lock for version bump

This enables complete multi-platform releases including:
- Linux x86_64 (GNU + musl)
- Linux aarch64 (musl)
- Linux armv7 (musl)
- macOS x86_64 + aarch64
- Windows x86_64

Refs #1874

Author: Test User

.docs/design-zig-ci-installation.md

@@ -0,0 +1,238 @@
+# Implementation Plan: Install Zig for Cross-Platform CI Builds
+
+**Status**: Draft
+**Research Doc**: `.docs/research-zig-ci-installation.md`
+**Author**: AI Agent (Claude Code)
+**Date**: 2026-05-27
+**Estimated Effort**: 2 hours
+
+## Overview
+
+### Summary
+Enable zig for all CI build targets by:
+1. Adding `Cross.toml` with pre-build commands to install zig in cross containers
+2. Adding zig installation step for Windows builds
+3. Fixing Docker workspace member path issue
+
+### Approach
+Use cross's built-in `pre-build` feature to install zig in Docker containers, and standard package managers for Windows.
+
+### Scope
+
+**In Scope:**
+- Create `Cross.toml` with zig pre-build for musl targets
+- Add Windows zig install step in workflow
+- Fix Docker workspace member issue
+- Test the complete workflow
+
+**Out of Scope:**
+- Replacing zlob with pure-Rust alternative
+- Forking cross Docker images
+- Custom Docker image builds
+- Fixing crates.io publishing issue (separate problem)
+
+**Avoid At All Cost:**
+- Hardcoding specific zig versions (use latest or env var)
+- Complex custom Dockerfiles
+- Breaking existing macOS builds
+
+## Architecture
+
+### Component Diagram
+
+```
+GitHub Actions Workflow
+├── Linux musl builds (cross)
+│   └── Cross.toml → pre-build: apt-get install zig
+│       └── Container now has zig → build succeeds
+├── Windows build
+│   └── Workflow step: choco install zig
+│       └── Runner now has zig → build succeeds
+├── macOS builds
+│   └── Already has zig → no changes
+└── Docker builds
+    └── Fix workspace member path → build succeeds
+```
+
+### Key Design Decisions
+
+| Decision | Rationale | Alternatives Rejected |
+|----------|-----------|----------------------|
+| Use `pre-build` in Cross.toml | Official cross feature, minimal complexity | Custom Docker images |
+| Use apt-get for Linux containers | Debian-based containers, most reliable | Download from ziglang.org |
+| Use chocolatey for Windows | Standard on GitHub-hosted runners | Scoop, manual download |
+| Fix Docker workspace issue | Simple path fix in Dockerfile | Restructure workspace |
+
+### Simplicity Check
+
+> "What if this could be easy?"
+
+The simplest solution:
+1. One `Cross.toml` file with 3 pre-build lines
+2. One workflow step for Windows
+3. One Dockerfile edit
+
+**Senior Engineer Test**: Is this overcomplicated? No - it's using built-in features.
+
+## File Changes
+
+### New Files
+| File | Purpose |
+|------|---------|
+| `Cross.toml` | cross configuration with zig pre-build |
+
+### Modified Files
+| File | Changes |
+|------|---------|
+| `.github/workflows/release-comprehensive.yml` | Add Windows zig install, fix Docker issue |
+| `Dockerfile` or `.github/workflows/docker-multiarch.yml` | Fix workspace member path |
+
+## Implementation Steps
+
+### Step 1: Create Cross.toml
+**File:** `Cross.toml`
+**Description:** Configure cross to install zig before building musl targets
+
+```toml
+[target.aarch64-unknown-linux-musl]
+pre-build = [
+    "apt-get update && apt-get install -y snapd",
+    "snap install zig --classic --beta",
+]
+
+[target.x86_64-unknown-linux-musl]
+pre-build = [
+    "apt-get update && apt-get install -y snapd",
+    "snap install zig --classic --beta",
+]
+
+[target.armv7-unknown-linux-musleabihf]
+pre-build = [
+    "apt-get update && apt-get install -y snapd",
+    "snap install zig --classic --beta",
+]
+```
+
+Wait - snap may not work in Docker containers. Let me use a different approach.
+
+Better approach - download zig directly:
+```toml
+[target.aarch64-unknown-linux-musl]
+pre-build = [
+    "apt-get update && apt-get install -y curl xz-utils",
+    "curl -L https://ziglang.org/builds/zig-linux-x86_64-0.16.0-dev.1234+abcdef.tar.xz -o /tmp/zig.tar.xz",
+    "tar -xf /tmp/zig.tar.xz -C /usr/local --strip-components=1",
+]
+```
+
+Actually, the simplest and most reliable approach is to use the official zig download:
+
+```toml
+[target.aarch64-unknown-linux-musl]
+pre-build = [
+    "apt-get update && apt-get install -y wget tar xz-utils",
+    "wget -q https://ziglang.org/download/0.13.0/zig-linux-x86_64-0.13.0.tar.xz -O /tmp/zig.tar.xz",
+    "tar -xf /tmp/zig.tar.xz -C /tmp",
+    "cp /tmp/zig-linux-x86_64-0.13.0/zig /usr/local/bin/zig",
+    "chmod +x /usr/local/bin/zig",
+]
+```
+
+But we want to avoid hardcoding versions. Let me check if we can use the latest version or apt.
+
+Actually, for Ubuntu/Debian, there's a simpler way - use the official zig PPA or just download the latest stable version.
+
+Let me use a more robust approach that works with any version:
+
+```toml
+[target.aarch64-unknown-linux-musl]
+pre-build = [
+    "apt-get update && apt-get install -y curl tar xz-utils",
+    "curl -s https://ziglang.org/download/index.json | grep -o 'https://.*zig-linux-x86_64-[^\"]*\\.tar\\.xz' | head -1 | xargs -I {} curl -L {} -o /tmp/zig.tar.xz",
+    "tar -xf /tmp/zig.tar.xz -C /tmp",
+    "cp /tmp/zig-*/zig /usr/local/bin/zig",
+    "chmod +x /usr/local/bin/zig",
+    "zig version",
+]
+```
+
+This dynamically fetches the latest zig version.
+
+**Tests:** Build locally with cross
+**Estimated:** 30 minutes
+
+### Step 2: Add Windows zig installation
+**File:** `.github/workflows/release-comprehensive.yml`
+**Description:** Add step to install zig on Windows runner
+
+```yaml
+- name: Install zig (required by zlob dependency)
+  if: contains(matrix.target, 'windows')
+  run: |
+    choco install zig
+    zig version
+```
+
+**Tests:** Verify Windows build succeeds
+**Estimated:** 15 minutes
+
+### Step 3: Fix Docker workspace issue
+**File:** `.github/workflows/docker-multiarch.yml` or Dockerfile
+**Description:** The Docker build fails because it doesn't copy `infrastructure/` but workspace expects it.
+
+Options:
+1. Add `infrastructure/` to Docker COPY commands
+2. Remove `infrastructure/*` from workspace members and make it a separate workspace
+3. Use `--exclude infrastructure` in cargo build
+
+The simplest fix is option 1 - copy infrastructure into the Docker context.
+
+**Estimated:** 30 minutes
+
+### Step 4: Test workflow
+**Description:**
+1. Commit changes
+2. Push to main
+3. Create test tag or re-run workflow
+4. Verify all builds succeed
+
+**Estimated:** 30 minutes
+
+## Rollback Plan
+
+If issues discovered:
+1. Revert Cross.toml
+2. Revert workflow changes
+3. macOS builds will still work (unaffected)
+
+## Dependencies
+
+### New Dependencies
+None
+
+### External Tools
+- curl (in cross containers)
+- tar (in cross containers)
+- xz-utils (in cross containers)
+- chocolatey (on Windows runners)
+
+## Performance Considerations
+
+### Expected Impact
+- Pre-build adds ~30-60 seconds per musl build
+- Windows zig install adds ~30 seconds
+- Total workflow time increase: ~2-3 minutes
+
+## Open Items
+
+| Item | Status | Owner |
+|------|--------|-------|
+| Verify cross container has internet | Pending | Test in CI |
+| Verify chocolatey works on Windows | Pending | Test in CI |
+| Determine correct zig version | Pending | Use latest stable |
+
+## Approval
+
+- [ ] Technical review complete
+- [ ] Test strategy approved
+- [ ] Human approval received