[feat](trx-frontend-http): per-entry interleave time in TimeSpan scheduler

Each ScheduleEntry can now carry its own interleave_min, overriding the
config-level default for that slot in the cycle.  The cycle length is the
sum of all active entries' effective durations (weighted), so entries with
longer individual interleave times occupy proportionally more time.

UI: "Interleave (min, optional)" input in the add-entry form; value shown
in the entries table (displays "—" when using the config default).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -724,7 +724,7 @@
           </div>
           <table class="sch-ts-table">
             <thead>
-              <tr><th>Start</th><th>End</th><th>Bookmark</th><th>Label</th><th></th></tr>
+              <tr><th>Start</th><th>End</th><th>Bookmark</th><th>Label</th><th>Interleave (min)</th><th></th></tr>
             </thead>
             <tbody id="scheduler-ts-tbody"></tbody>
           </table>
@@ -741,6 +741,9 @@
             <label class="sch-label">Label (optional)
               <input type="text" id="scheduler-ts-label" class="status-input" placeholder="e.g. 40m FT8" />
             </label>
+            <label class="sch-label">Interleave (min, optional)
+              <input type="number" id="scheduler-ts-entry-interleave" class="status-input" min="1" max="60" placeholder="default" style="width:6rem;" />
+            </label>
             <button id="scheduler-ts-add-btn" class="sch-write" type="button">+ Add</button>
           </div>
         </div>