docs: second-pass boot audit (D-Bus honesty, shell quality, login), archive 4 stale docs

BOOT-PROCESS-SECOND-AUDIT-2026-05-03.md: deep dive into:
- D-Bus implementation honesty (15/19 login1 methods real, not stubs)
- ion shell quality matrix (vs bash/dash)
- Login prompt completeness (getty→login→ion chain)
- Per-subsystem hardware init status (storage/display/input/network/USB/audio/ACPI)
- Implementation plan Phases F1-F6

Archived 4 completed/deferred plans: GRUB, VFAT, USB-BOOT-INPUT, ZSH-PORTING

local/docs/archived/README.md

@@ -13,5 +13,9 @@ current plans. They are kept for reference only.
 | `GREETER-LOGIN-ANALYSIS.md` | `GREETER-LOGIN-IMPLEMENTATION-PLAN.md` |
 | `INTEL-HDA-IMPLEMENTATION-PLAN.md` | (Deferred — audio is P3 priority) |
 | `ACPI-I2C-HID-IMPLEMENTATION-PLAN.md` | (Deferred — USB HID is primary input path) |
+| `GRUB-INTEGRATION-PLAN.md` | GRUB is fully implemented (redbear-grub config, installer support, grub recipe) |
+| `VFAT-IMPLEMENTATION-PLAN.md` | VFAT is fully implemented (fatd, fat-mkfs, fat-label, fat-check) |
+| `USB-BOOT-INPUT-PLAN.md` | Superseded — USB HID in initfs, USB storage in initfs (Phase B2) |
+| `ZSH-PORTING-PLAN.md` | Deferred indefinitely — ion is the default shell |
 
 ## Date archived: 2026-05-03