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.

kernel/rv1106-enablement/usb/rv1106_usb2phy_cfg.c.frag

@@ -1,7 +1,7 @@
  * RV1106 USB2 PHY: single OTG port at 0xff3e0000 (ported from the vendor driver;
  * fields map 1:1 to 6.18 except utmi_iddig -> utmi_id, and the 5.10-only
  * iddig_output/iddig_en/bvalid_grf_sel are dropped). Signal-quality phy_tuning is
- * left off for now (guarded, so NULL is safe) — the phy is functional without it.
+ * left off for now (guarded, so NULL is safe): the phy is functional without it.
  */
 static const struct rockchip_usb2phy_cfg rv1106_phy_cfgs[] = {
 	{