Implement semantic commit messages for environment merges

[jsham042]

This PR updates the merge command to follow semantic commit conventions, improving git history consistency and enabling better automated tooling.

Changes

• Added fmt package import to support string formatting
• Updated merge commit message from "Merge environment <env>" to fmt.Sprintf("chore(merge): merge environment %s", env)
• Maintained all existing functionality - stash handling, stdout/stderr wiring, and error handling remain unchanged

Before

cmd := exec.CommandContext(ctx, "git", "merge", "-m", "Merge environment "+env, "--", "container-use/"+env)

After

cmd := exec.CommandContext(ctx, "git", "merge", "-m", fmt.Sprintf("chore(merge): merge environment %s", env), "--", "container-use/"+env)

Benefits

• Consistent git history - All merge commits now follow semantic commit conventions
• Better tooling support - Enables automated changelog generation and version bumping
• Improved readability - Clear type (chore) and scope (merge) for each merge operation
• Searchable commits - Easier to filter and find merge-related commits

Example Output

Instead of: "Merge environment production"
Now produces: "chore(merge): merge environment production"

Still needs testing and validation

Fixes #100

[cwlbraa]

i'm afraid that characterizing all merges as chore throws away quite a bit of semantics, and merge is not really a scope.