fix(install): resolve repo_version placeholder in driver dry-run output

[r0x0r]

Summary

rocm install driver --dry-run printed an unexpanded shell-style placeholder on the repo_version: line:

repo_version: ${ROCM_CLI_AMDGPU_VERSION:-7.2.4}

The literal ${ROCM_CLI_AMDGPU_VERSION:-7.2.4} template was emitted verbatim instead of being resolved to the effective version.

Root cause

The driver install plan stores the repo version as a shell parameter-expansion template so it can be embedded verbatim into the shell commands that later expand it at runtime. The human-readable plan summary printed the same template on its repo_version: line, leaking the raw shell placeholder into user-facing output.

Fix

Resolve the template to its effective value for display only:

• the value of ROCM_CLI_AMDGPU_VERSION when set and non-empty (matching shell :- semantics), otherwise the 7.2.4 default.

The executable commands still carry the literal template, so the runtime shell resolves it as before — only the summary line changes.

Before:

repo_version: ${ROCM_CLI_AMDGPU_VERSION:-7.2.4}

After (env unset):

repo_version: 7.2.4

Tests

Added:

• resolve_repo_version_uses_default_when_env_unset
• resolve_repo_version_prefers_env_value_when_set
• resolve_repo_version_treats_empty_env_as_unset
• resolve_repo_version_passes_through_non_template
• driver_plan_dry_run_repo_version_line_is_resolved — render-level regression asserting the dry-run summary shows the resolved version and not the raw placeholder.

The regression test fails before the fix (summary line showed the raw placeholder) and passes after.

Verification

• cargo fmt -p rocm
• cargo clippy -p rocm --all-targets -- -D warnings
• cargo test -p rocm --bin rocm driver_plan (20 passed) and the new resolver tests

This is a cosmetic/clarity change to dry-run output; no behavior change to the executed commands.