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/wifi/wifi-dt-block.dtsi

@@ -20,7 +20,7 @@
 	status = "okay";
 };
 
-/* --- M5: AIC8800DC wifi/BT SDIO (on &sdmmc, mmc@ffaa0000 — NOT &sdio) --- */
+/* --- M5: AIC8800DC wifi/BT SDIO (on &sdmmc, mmc@ffaa0000, NOT &sdio) --- */
 &sdmmc {
 	max-frequency = <50000000>;
 	bus-width = <4>;