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/0007-public-repo-hosted-kernel-build.md

@@ -1,4 +1,4 @@
-# ADR 0007 — Hosted-Only CI
+# ADR 0007: Hosted-Only CI
 
 **Status:** Accepted (2026-08-30). Supersedes the runner half of ADR-0004.
 
@@ -8,7 +8,7 @@ alignment with the stack philosophy). Two facts change the ADR-0004 calculus:
 
 1. **A self-hosted runner on a public repo is a standing hazard.** A fork PR
    can modify workflow files; once any run of theirs is approved, workflows
-   can target the repo's registered self-hosted runners — i.e. arbitrary code
+   can target the repo's registered self-hosted runners, i.e. arbitrary code
    on the private host, which also serves production. GitHub's own guidance is
    to never attach self-hosted runners to public repos, and personal-account
    repos have no runner groups to scope the risk away.