Make shim boot path detection case-insensitive

[Amodak9801]

Summary

• show_var_path() detected shim with sequential strstr() on /File(\EFI\, \shim, and .efi). Firmware often rewrites the loader to SHIMX64.EFI, so is_shim stayed false and optional data was not formatted as a second File(...).
• Switch those searches to strcasestr (we already build with _GNU_SOURCE) so uppercase and mixed-case paths match. Lowercase shimx64.efi is unchanged.

Fixes #223

Test plan

• On a UEFI machine or QEMU+OVMF, run efibootmgr -v against an entry whose path is SHIMX64.EFI (or create \EFI\<distro>\shimx64.efi and let firmware uppercase it). Optional data should display as File(...), not dotted UCS-2.
• Confirm a lowercase shimx64.efi entry still formats the same as before.
• Confirm a non-shim path such as grubx64.efi / GRUBX64.EFI is not treated as shim.

I could not run make in this environment (make and efivar devel packages are not installed). The change is the one-line strstr → strcasestr swap in show_var_path().

Made with Cursor

[Amodak9801]

Gentle ping — this is ready for review when you have a moment.

One-line change: show_var_path() uses strcasestr so firmware-rewritten SHIMX64.EFI is treated as shim (Fixes #223). Happy to adjust the matcher or add UEFI/efibootmgr -v notes if that would help.

[Amodak9801]

Gentle ping — still ready for review when you have a moment.

One-line change: show_var_path() uses strcasestr so firmware-rewritten SHIMX64.EFI is treated as shim (Fixes #223).

The ci.yml run on this PR expired after 30 days waiting for workflow approval from a maintainer (fork PR). Happy to rebase or adjust if needed.