fix(installer): harden the lock path against the AMD-iGPU DPMS lockout

An idle lock on this Strix Halo box wedged the whole session: hyprlock died and the compositor stayed locked with no prompt, recoverable only from a console. It's a documented AMD-integrated-Radeon failure (hyprlock#953, Hyprland#5822) -- a display power cycle via DPMS invalidates the GPU resources the lock client holds, so hyprlock loses its surface and exits without unlocking. No coredump, no OOM; the GPU pulls the rug out.

Two installer changes, both scoped and tested:

update_grub_cmdline adds amdgpu.runpm=0 on AMD machines only. Disabling GPU runtime power management keeps those resources valid across a display cycle -- the root fix. A no-op on Intel/NVIDIA, and it rides the existing merge so no boot-critical token is touched.

configure_hyprlock_pam writes a complete PAM stack. The hyprlock package ships only `auth include login`, leaving account and session uninitialised so pam_end() crashes on cleanup -- a separate documented lockout cause. All three phases now resolve through login, inheriting the keyring the graphical login uses.

CALL_SITES pins both new wirings. 372 unit tests, exit 0; each addition proven by reverting it.

0 files changed, 0 insertions, 0 deletions