feat(core,view): input cards with change tracking (plan B1 · C2)

- Three values per pier: defaults (as imported), input (generated), draft
  (current cards). Overrides = draft vs defaults; pending = draft vs input.
- Editable now: 코핑 폭, 코핑 길이, 말뚝 길이. Changing a card does not touch the
  3D view until 다시 생성; the header and the card show 변경 n.
- Revert puts a field back to its imported default.
- Project files store defaults and draft (optional; v1 files still open).
- Tests: 코핑 폭 3100 → 3300 gives one override and one pending change;
  regenerating clears pending but keeps the override; revert; file round trip.
- Not verified in a browser (no debuggable Chrome in this session).

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

index.html

@@ -89,6 +89,12 @@
       <section class="panel inputs" aria-labelledby="input-title">
         <h2 id="input-title">입력값</h2>
         <dl id="inputs" class="kv wide"></dl>
+        <section class="edit-card" aria-labelledby="edit-title">
+          <h3 id="edit-title">코핑·말뚝 입력 수정</h3>
+          <div id="edit-fields"></div>
+          <p id="edit-summary" class="muted small"></p>
+          <button id="edit-regen" class="btn primary" type="button" disabled>다시 생성 · 변경 0</button>
+        </section>
       </section>
     </div>