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.

docs/decisions/0008-panel-devenv-positioning.md

@@ -1,11 +1,11 @@
-# ADR 0008 — Panel Development Environment
+# ADR 0008: Panel Development Environment
 
 **Status:** Accepted (2026-08-30).
 
 ## Context
 warden-sdk was written as the SDK for WardenOS, and its documentation framed
 it that way: a support repo for one product. Since going public (ADR-0007,
-GPL-2.0-only), the actual audience is wider — anyone with a Luckfox Pico 86
+GPL-2.0-only), the actual audience is wider: anyone with a Luckfox Pico 86
 Panel gets a maintained 6.18 kernel, an off-device development loop, and a
 device simulator out of this repo, none of which exists elsewhere for this
 board. The product-first framing undersold that and confused the entry point
@@ -16,8 +16,8 @@ Position warden-sdk as **a modern, open development environment for the
 Luckfox Pico 86 Panel (RV1106)**. WardenOS is documented as the downstream
 consumer it is, not the purpose. Documentation follows three rules: lead with
 the board, not the product; keep private-repo references clearly marked as
-context; keep titles short — a heading names a section, it does not summarize
-it.
+context; keep titles short (a heading names a section,, it does not summarize
+it).
 
 ## Consequences
 - README and top-level docs lead with the hardware and the developer loop