docs: ASCII typography and style normalization across all repo text

Replace every em dash with real punctuation (rewrites, not hyphen swaps)
in docs, code comments, scripts, configs, and the port records; convert
en dashes, curly quotes, ellipsis glyphs, arrows, and section signs to
ASCII; drop machine-writing tell phrases from living docs. ADR titles
now use a colon. The M2 bring-up DTS model string carried an em dash
into the patch series and its record echoes; fixed at both, and the full
series re-verified to apply cleanly onto pristine 6.18.46. One comment
in freshness.h deliberately names the em dash glyph the UI renders as
the unknown mark; that is data, kept as prose naming it.

Verified: cargo tests (sim, config-lint, rs485-bridge), shellcheck,
both driver MC/DC harnesses, patches-apply.

qemu/configs/virt.fragment

@@ -1,4 +1,4 @@
-# QEMU -M virt kernel variant — merged onto build/warden_defconfig via
+# QEMU -M virt kernel variant, merged onto build/warden_defconfig via
 # WARDEN_KCONFIG_FRAGMENT (see build/build-kernel.sh). The RV1106 zImage stays
 # canonical and byte-identical when the variable is unset.
 #
@@ -18,7 +18,7 @@ CONFIG_PCI_HOST_GENERIC=y
 # shows up as ttyS0; stage-2 init aliases it to the device's /dev/ttyS4).
 CONFIG_SERIAL_8250_PCI=y
 
-# /dev/watchdog for flared's watchdog_loop() — untestable on both existing
+# /dev/watchdog for flared's watchdog_loop(), untestable on both existing
 # sims. i6300esb is the watchdog QEMU offers on arm virt (PCI device):
 # -device i6300esb -action watchdog=reset.
 CONFIG_WATCHDOG=y
@@ -28,7 +28,7 @@ CONFIG_I6300ESB_WDT=y
 CONFIG_WIREGUARD=y
 
 # Display + touch: virtio-gpu scanout with fbdev emulation (the VM UI build
-# uses LVGL's fbdev backend — no libdrm needed in the guest), virtio-tablet
+# uses LVGL's fbdev backend; no libdrm needed in the guest), virtio-tablet
 # for absolute-coordinate touch injection via QMP.
 CONFIG_FB=y
 CONFIG_DRM_VIRTIO_GPU=y