The Clear All confirmation was the last destructive task action still
running through window.showConfirmation (the legacy dialog system) —
visually inconsistent with the rest of the tasks page (single-row delete,
Uninstall, etc., which all use openEoModal). Switches it to the same
eo-modal shape used by _showDeleteTaskModal so the destructive-confirm
family looks unified.
While here, adds a "Cancel running tasks too" toggle inside the modal,
off by default. Backed by the existing .eo-toggle.eo-toggle-card style
(modal.css). Drives a new opts.cancelRunning in performClearAll:
Off → skip any running/queued/pending tasks; only terminal rows
are deleted. The success toast reports the split.
On → cancel each active task first (POST /cancel), wait for the
terminal status via SSE, then delete (with the 409→force
fallback the single-row deleteTask already uses).
Body composition mirrors the per-task delete modal:
- danger empty-state ("This cannot be undone")
- badge row with Total / Running / Terminal counts
- the toggle (only shown when runningCount > 0 — no need otherwise)
The action button's label live-updates as the toggle changes:
toggle off + running rows → "Delete N (skip M running)"
toggle on / no runners → "Delete N Tasks"
So the user sees exactly what they're about to do before clicking.
Cancel / backdrop / X all resolve to no-op (same contract as
_showDeleteTaskModal). Modal returns {confirmed, cancelRunning} so the
caller knows which path to take.
Sets up the multi-select work next: the modal already accepts an
arbitrary tasks array; the upcoming "Delete selected" is a one-line
call into the same _showClearAllModal with a filtered list.
Signed-off-by: librelad <librelad@digitalangels.vip>