Fix boot-to-login: override pcid-spawner to oneshot_async, add U3 input producers, Intel HDA phases A-D

- Override 00_pcid-spawner.service to oneshot_async in redbear-legacy-base.toml:
  rootfs phase no longer blocks on PCI driver init; getty/login starts immediately.
  Confirmed working on both QEMU and bare metal (redbear-live-mini).
- Clean up 00_base legacy script: remove dead notify ipcd/ptyd calls, keep sudo --daemon.
- Add U3 named input producers: inputd supports per-device named producers with
  fan-out to both device-specific consumers and legacy VT consumers. Migrate ps2d
  and usbhidd to InputProducer trait. RESERVED_DEVICE_NAMES deduplicated.
- Add Intel HDA audio driver phases A-D: ihdad error handling (37 fixes), audio
  quirks, codec path enumeration, mixer/volume control.
- Add init service start/readiness logging (always visible, not debug-gated).
- Update BOOT-PROCESS-ASSESSMENT.md: Phase 6 complete, boot procedure documented,
  validation matrix updated with confirmed boot status.
- Update USB-IMPLEMENTATION-PLAN.md and INPUT-SCHEME-ENHANCEMENT.md for U2/U3 status.

config/redbear-legacy-base.toml

@@ -1,8 +1,31 @@
-# Red Bear OS overrides for broken legacy base init scripts.
+# Red Bear OS overrides for legacy base init scripts.
+#
+# 00_base: tmpdir setup + sudo --daemon. ipcd and ptyd are started by the
+#          systemd-style services in base recipe's init.d/ (00_ipcd.service,
+#          00_ptyd.service). The old "notify" calls have been removed because
+#          the "notify" binary does not exist — they always failed silently.
+#          sudo --daemon is kept here because 00_sudo.service exists in the base
+#          recipe but is not wired into any target that gets scheduled.
+# 00_drivers: removed — pcid-spawner is started by 00_pcid-spawner.service from
+#             the base recipe. The legacy script was redundant.
+# 10_net: blanked — replaced by per-config network services (e.g. redbear-live-mini's
+#         10_smolnetd.service + 10_dhcpd.service).
+# 00_pcid-spawner.service: overridden to oneshot_async. The base recipe uses
+#          type="oneshot" which blocks init until pcid-spawner exits. On real
+#          hardware (and QEMU), pcid-spawner can hang waiting for a PCI device
+#          driver that never responds, blocking the entire rootfs phase including
+#          getty/login. Using oneshot_async lets init proceed to start console
+#          services while drivers spawn in the background.
 
 [[files]]
 path = "/usr/lib/init.d/00_base"
-data = ""
+data = """
+# clear and recreate tmpdir with 0o1777 permission
+rm -rf /tmp
+mkdir -m a=rwxt /tmp
+
+nowait sudo --daemon
+"""
 
 [[files]]
 path = "/usr/lib/init.d/00_drivers"
@@ -23,3 +46,14 @@ default_dependencies = false
 cmd = "audiod"
 type = "oneshot_async"
 """
+
+[[files]]
+path = "/etc/init.d/00_pcid-spawner.service"
+data = """
+[unit]
+description = "PCI driver spawner (non-blocking)"
+
+[service]
+cmd = "pcid-spawner"
+type = "oneshot_async"
+"""