Hotfix: planner init crashed for admin accounts, killing autosave and the plans list

The admin nav-link reveal ran before the generated nav existed
(getElementById('nav-admin') was null only for admins — which is why
tests and non-admin checks missed it), aborting init before form wiring,
autosave, and loadPlans. initSideNav now runs first, the reveal is
null-safe, and wireCuppingLink degrades instead of crashing (its button
lost its home when After-the-Roast moved — it now lives at the end of
the Roast Log section with a pointer to the Roasts page).

Also: the Roasts page graph now honors the planner's °C/°F preference.

Co-Authored-By: Claude Fable 5 <[email protected]>

public/index.html

@@ -1169,6 +1169,19 @@
                   Draw from lot
                 </button>
               </div>
+              <div
+                style="display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-top:12px"
+              >
+                <button type="button" class="ghost-btn" id="btn-open-cupping">
+                  Open cupping session
+                </button>
+                <span class="field-note" id="cupping-link-note" style="margin:0"></span>
+              </div>
+              <p class="field-note">
+                After the roast, upload the .alog on the
+                <a href="/roasts">Roasts page</a> — weights, colour, cup notes,
+                and "one change next batch" now live there with the LLM review.
+              </p>
             </div>
           </section>