docs: v0.1.0 alpha framing + hygiene pass (#25)

Update the public-facing docs to the M-49 state (v0.1.0 alpha, first
full-campaign playtest: 19/21 missions completable, D191 crashes Bunker ii
+ Statue, D193 AI pacing is the top flaw).

- README: lead with what it is + status, research angle second; new
  Quick start section; Status/Download rewritten for the alpha + dual
  platform; "By the numbers" refreshed (~3 weeks, ~320 commits, ~190
  findings, ~49 sessions, 69 PORT files).
- .github/release-notes.md: v0.1.0 title + known-issues rewrite.
- .github/social-preview.html: status/stat lines (regen + re-upload the
  PNG separately).
- docs/index.md, docs/dev/LEVEL-STATUS.md: M-49 status.
- docs/dev/findings.md, docs/dev/GRAPHICS-BACKLOG.md: D191-D197 +
  D148/D170/D173 M-49 escalations.

Hygiene:
- Fix the `&` literal in internals.md H1.
- Repoint two ../README.md links that 404 on the Pages site.
- Standardise British -> American spelling across the public docs
  (behaviour->behavior, colour->color, catalogue->catalog,
  centre->center, etc.). Deep internal logs left untouched.
- .gitignore: document the local-notes convention (docs/HANDOFF.md,
  docs/BACKLOG.md, and a new docs/dev/notes/ drop for roadmaps and
  session plans) so it survives a fresh clone.

.github/release-notes.md

@@ -1,15 +1,20 @@
-## GoldenEye 007 PC Port — alpha
+## GoldenEye 007 PC Port — v0.1.0 alpha
 
-> ⚠️ **Very early research alpha. Not a playable game.**
-> The intro and menus render and all 21 solo missions load, but:
-> - **no audio** (Phase 3, not started);
+> ⚠️ **Research alpha. Playable, not polished.**
+> The full single-player campaign runs. In a full-campaign playtest on this
+> build, **19 of 21 missions were completable start to finish**. Known issues:
+> - **no audio** (Phase 3, not started) — the game runs silent;
+> - **two levels crash mid-mission** — Bunker ii and Statue (one root cause, D191);
+> - **AI characters move too slowly**, which breaks Cradle (the final level)
+>   via Trevelyan's scripted behavior (D193);
+> - **cutscenes frequently glitch** — skipped, wrong camera, misplaced actors (D148/D160);
 > - some front-end 3D models are broken (the spinning Nintendo logo, the
 >   MISSION COMPLETE / mode-select models);
 > - outdoor levels render with a **black sky**;
-> - expect crashes and glitches once past the level intro.
+> - mouse aim and some textures/transparency have rough edges.
 >
-> This is a technical demo of the porting work. If you want to *play* GoldenEye
-> on PC, use one of the Xbox 360 recompilation projects instead — see the
+> If you just want to *play* GoldenEye on PC today, use one of the Xbox 360
+> recompilation projects instead — see the
 > [project README](https://github.com/jkdansereau/goldeneye-pc-port#how-this-differs-from-the-other-goldeneye-pc-projects).
 
 ### Downloads

.github/social-preview.html

@@ -124,12 +124,12 @@
     <div class="rep">REPORT:</div>
 
     <div class="rows">
-      <div class="statusline">Status: <span class="status">PHASE 2 OF 4 &mdash; RENDERING</span></div>
+      <div class="statusline">Status: <span class="status">ALPHA v0.1.0 &mdash; PHASE 2 OF 4</span></div>
       <div class="stats">
-        <span class="k">Statistics:</span><span>21 / 21 solo missions load &amp; render</span>
+        <span class="k">Statistics:</span><span>19 / 21 solo missions completable in a full playthrough</span>
         <span></span><span>~230 game-code units, compiled unmodified</span>
         <span></span><span>~17k lines C/C++ &nbsp;&middot;&nbsp; ~6k Python  (port layer + tools)</span>
-        <span></span><span>162 bugs root-caused &nbsp;&middot;&nbsp; built in ~2 weeks, part-time</span>
+        <span></span><span>~190 bugs root-caused &nbsp;&middot;&nbsp; built in ~3 weeks, part-time</span>
       </div>
     </div>