[cpunion]

Follow up to #53: test the minimum supported LLGo release, v1.0.8, using its immutable commit SHA with the tag noted inline. The supported range remains LLGo >= 1.0.8.

Run that release's dependency setup on Ubuntu 24.04: ubuntu-latest now uses Ubuntu 26.04, which removed apt-key; v1.0.8 also expects Python 3.12 packages. Keep the existing Go/LLVM versions and test coverage, and clarify the LLVM 22 assertion comment.

Validation:

• Local macOS arm64: go build -v ./... and all native-binding/demangle CI test commands pass with v1.0.8.
• All four CI jobs passed before the SHA/comment refinement; verified the pinned SHA is the same release source. Latest CI is rerunning.
• No new actionlint diagnostics (four pre-existing).

[fennoai]

Review summary

This PR switches the llgo-test job's LLGo checkout from an immutable commit SHA to the mutable git tag v1.0.8, aligning CI with the stated goal of testing the minimum supported LLGo release. The change is small and functionally sound:

• v1.0.8 includes the native-variable support from xgo-dev/llgo#2882 that the removed SHA pin was tracking, so the native-binding tests (lines 68–84) keep the support they rely on.
• v1.0.8's setup-deps action defaults to LLVM 22, so the hardcoded '22' (line 55) and the = 22 assertion (line 62) remain valid.

Two non-blocking items — one inline, one that falls outside the diff hunk:

Stale comment (line 60, outside this diff): # Use the LLVM binding version declared by the pinned compiler. still calls the checkout a "pinned compiler," but the ref is now a tag. It also describes a version-derivation flow the step doesn't actually perform — the step hardcodes 22 (line 55) and merely asserts llvm-config --version matches it (line 62), rather than reading a version "declared by" the compiler. Worth rewording while this block is touched, e.g. # Assert llvm-config matches the LLVM 22 required by LLGo v1.0.8.