Inline editable fields (init/hp/maxhp/ac) with editing overlay

Participant card fields now editable in place (D-style): transparent bg,
underline on hover/focus, no spinners. Covers Initiative, Current HP, Max HP,
and AC badge value.

Click any value to edit. Blur/Enter saves. Escape cancels. Status recomputes
on HP change (conscious/dying/dead/down per ruleset).

Editing overlay: when a field is focused, amber ring highlights the card and
a centered pointer-events-none label shows '✎ Editing {field}'. Label floats
over card middle without blocking input — taps pass through to field.

Handlers: handleInlineCurrentHp (recomputes status), handleInlineMaxHp,
handleInlineAc. Keys prefixed to avoid React key collisions when values match.

Tests: selectors updated to use element id (monsterMaxHp) since inline
aria-labels now match form label queries.

src/tests/ReslotAllPaths.test.js

@@ -16,7 +16,7 @@ function lastParticipantsUpdate() {
 async function addOne(form, name, hp, mod, init) {
   fireEvent.change(form.getByPlaceholderText('e.g., Dire Wolf'), { target: { value: name } });
   fireEvent.change(form.getByLabelText(/Init Mod/i), { target: { value: String(mod) } });
-  fireEvent.change(form.getByLabelText(/Max HP/i), { target: { value: String(hp) } });
+  fireEvent.change(document.getElementById('monsterMaxHp'), { target: { value: String(hp) } });
   fireEvent.change(form.getByPlaceholderText('auto'), { target: { value: String(init) } });
   fireEvent.click(form.getByRole('button', { name: /Add to Encounter/i }));
   await waitFor(() => {