fix(gen-keybinds): match the section dash as a literal so headers survive LC_ALL=C

The section rule was `/^[[:space:]]*\/\/[[:space:]]*─+ (.+) ─+…$/`, a quantifier on a
multibyte character. Under LC_ALL=C — which is what cron, systemd user units and agent
shells get, regardless of LANG — gawk matches byte-wise, so `─+` means "the last byte of
U+2500, repeated" and never matches. Measured on the live keybinds.kdl: the old script
emitted 0 section headers instead of 12, all 120 binding rows intact, exit status 0. A
silent one-third-of-the-page loss, invisible to any caller that only checks the status.

The dash is now matched and stripped as a literal (`gsub(/─/, "")`), which is byte-safe
in every locale, and a comment must be dash-decorated on both sides to open a section, so
plain comments are still ignored. A test pins the C-locale case explicitly, because the
box's own terminal has always been UTF-8 and could never have caught this.

The committed artifact omp-docs/tools/niri/keybindings.md is unaffected (12 headers,
120 rows — it was generated from a UTF-8 shell); output is now identical either way.

scripts/gen-keybinds.sh

@@ -42,17 +42,27 @@ gen() {
   echo "> GENERATED by \`scripts/gen-keybinds.sh\` from \`$(basename "$KBD")\` — do not edit by hand."
   echo
   awk '
-    # section header: // ─── Name ───
-    /^[[:space:]]*\/\/[[:space:]]*─+ (.+) ─+[[:space:]]*$/ {
+    # Section marker: a comment decorated with box-drawing dashes on both sides,
+    # `// ─── Name ───`. The dash is matched as a LITERAL and removed with gsub — never
+    # with a quantifier on the multibyte character. Under LC_ALL=C (cron, systemd units,
+    # agent shells) gawk works byte-wise, `─+` then means "the last byte of ─, repeated",
+    # and every header vanishes while the script still exits 0. Plain comments stay
+    # comments: only a dash-decorated one opens a section.
+    /^[[:space:]]*\/\/[[:space:]]*─/ {
       s = $0
-      sub(/^[[:space:]]*\/\/[[:space:]]*─+ /, "", s)
-      sub(/ ─+[[:space:]]*$/, "", s)
-      if (in_table) print ""
-      print "## " s
-      print ""
-      print "| Key | Action |"
-      print "|-----|--------|"
-      in_table = 1
+      sub(/^[[:space:]]*\/\/[[:space:]]*/, "", s)
+      sub(/[[:space:]]+$/, "", s)
+      if (s ~ /─ .*─/) {
+        gsub(/─/, "", s)
+        gsub(/[[:space:]]+/, " ", s)
+        sub(/^ /, "", s); sub(/ $/, "", s)
+        if (in_table) print ""
+        print "## " s
+        print ""
+        print "| Key | Action |"
+        print "|-----|--------|"
+        in_table = 1
+      }
       next
     }
     # bind line: KEY [flags] [hotkey-overlay-title="..."] { action; }

tests/gen-keybinds.bats

@@ -48,6 +48,16 @@ teardown() {
   [[ "$output" != *"a plain comment"* ]]
 }
 
+@test "section headers survive a C locale, where awk reads bytes instead of characters" {
+  # Cron, systemd units and agent shells get LC_ALL=C while Frank's terminal does not.
+  # A matcher that puts a quantifier on a multibyte character then loses EVERY section
+  # header and prints a sheet with no sections at all — silently, exit status 0.
+  run env LC_ALL=C "$GEN" "$TMP/keybinds.kdl"
+  [[ "$output" == *"## Applications"* ]]
+  [[ "$output" == *"## Screenshots"* ]]
+  [[ "$output" != *"a plain comment"* ]]
+}
+
 @test "row count matches bind count" {
   run "$GEN" "$TMP/keybinds.kdl"
   local rows