feat(mosstank): cast back-to-back, and a settings view for the thresholds

Three things from the first working buff pass.

**Pacing.** Casts were three seconds apart because of a fixed interval I added
before there was a real busy signal. There is one now -- the shared busy count,
incremented by the cast and decremented by the server's UseDone -- so the
interval is gone and the server is the only throttle. MossTank casts the moment
the previous action is acknowledged, which is the spam behaviour VTank has. The
stall timeout moved 25s -> 30s so a slow server does not read as a stall.

**Stamina to Mana was surprising.** VTank does convert vitals by default
(Recharge-*-Mana), so the behaviour is right, but a buff pass quietly spending
your stamina is not something to discover by watching. It is now a setting,
with its own thresholds, and can be turned off outright.

**Settings view.** Spell difficulty margin, rebuff time, the three vital
thresholds, and three toggles. Two details worth recording:

* The difficulty margin is SIGNED, per the VTank wiki: "a positive number
  raises the skill necessary to cast spells, a negative number lowers it. To
  attempt higher spells at a low level use a negative number." So the range
  spans -100..+100 rather than starting at zero.
* It is a second registered panel with a complementary visible binding rather
  than a tab control. Two panels and an Action need no new markup vocabulary,
  and only one is ever on screen.

Adjuster buttons rather than typed fields: buttons are proven in plugin markup,
while an editable UiField would need keyboard routing plumbed through to plugin
panels first. Worth doing, but not as a side quest inside this change.

Also fixed: the App copy target names plugin files explicitly, so the new
markup would have been left out of the plugin directory and the settings panel
would have failed to load at runtime with the build perfectly green. Caught by
listing the output rather than trusting the build.

Solution builds clean; 14,438 tests pass on the standard hermetic lane filter,
0 failures.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/AcDream.Plugins.MossTank.Tests/VitalPlanTests.cs

@@ -102,6 +102,16 @@ public class VitalPlanTests
         Assert.Equal(1u, pick.SpellId);
     }
 
+    [Fact]
+    public void DoesNothingWhenVitalUpkeepIsTurnedOff()
+    {
+        // Converting stamina mid-buff surprises people, so it has to be a
+        // setting rather than a behaviour.
+        var character = new Character { CurrentMana = 1, CurrentStamina = 100 };
+        var off = new VitalSettings { Enabled = false };
+        Assert.Equal(VitalAction.None, VitalPlan.Decide(character, off));
+    }
+
     [Fact]
     public void ReportsNoConversionWhenTheCharacterKnowsNone()
     {