document RP412MFDPROTRUDE for players (handbook + the shipped environ.ini)

The knob landed with only a source comment, so a player had no way to find
it.  Two channels, matching where the sibling display settings already live:

  - docs/rp412-handbook.html: a row in the "environ.ini - display layout"
    table beside L4MFDSCALE / L4RADARSCALE / L4RADARPOS, in that table's own
    voice (what it does, that it is a longer bar rather than a wider button,
    range and default).
  - RP_L4/RPL4ENVIRON.cpp: a commented block in the self-documenting default
    environ.ini the exe lays down on first run, placed at the end of the
    display-layout section after L4MAPSCALE.  Shown commented with an example
    value (10) since the default 0 means "leave the pod geometry alone" --
    uncommenting it is the action.

Both state the gotcha the type invites: it takes a NUMBER, and a word parses
to 0 (off).

Verified: RP_L4 rebuilds clean and the block reads back out of the freshly
linked rpl4opt.exe exactly as written, so a first run will lay it down.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

RP_L4/RPL4ENVIRON.cpp

@@ -178,6 +178,20 @@ namespace
 "L4MAPPOS=LEFT\n"
 "L4MAPSCALE=100\n"
 "\n"
+"# How far the lit buttons around each display reach past its edge, in\n"
+"# EXTRA pixels. The pod's buttons were physical and backlit; on a\n"
+"# desktop panel they are a thin bar along the glass edge, and a\n"
+"# FLASHING one is easy to miss. This lengthens that bar - the button\n"
+"# keeps its width and still reaches the same distance behind the\n"
+"# picture, so the display and the click target are unchanged. The red\n"
+"# MFD strips and the amber map columns only.\n"
+"#\n"
+"# 0 - the default - is the pod's own geometry, exactly as it shipped.\n"
+"# 1-200 adds that many pixels. Give it a number: a word counts as 0.\n"
+"# (BattleTech 4.11 carries the same setting defaulted to 10, where its\n"
+"# players asked for it; the two games are tuned separately.)\n"
+"#RP412MFDPROTRUDE=10\n"
+"\n"
 "# The Winners Circle: at the end of a race the finishers are stood on\n"
 "# the award platform in finishing order, with each pilot's callsign on\n"
 "# the plate beside their spot, and held there for a few seconds before\n"

docs/rp412-handbook.html

@@ -1133,6 +1133,7 @@
           <tr><th>L4MFDSCALE_<span style="color:var(--phosphor)">xx</span></th><td>Any one on its own — <span class="addr" style="font-family:var(--mono)">UL UC UR LL LR</span>. Unset inherits the line above.</td></tr>
           <tr><th>L4RADARSCALE</th><td>The radar alone. It already sits at 1.35× the MFDs.</td></tr>
           <tr><th>L4RADARPOS</th><td class="mono">CENTER · LEFT · RIGHT · MIDLEFT · MIDRIGHT</td></tr>
+          <tr><th>RP412MFDPROTRUDE</th><td>Extra pixels of lit button reaching past each display edge, so a flashing one is easier to catch. A longer bar, not a wider button — the picture and the click target are unchanged. <span style="color:var(--ink-quiet)">0–200, default 0 (the pod's own geometry)</span></td></tr>
         </tbody>
       </table>
     </div>