feat(tickets): filtres multi-critères par cases à cocher (backend + frontend)

Passe les filtres de la liste des tickets en sélection multiple (#12).

Backend Rust :
- IssueListFilter : statuses/priorities en Vec, filter_matches en OR intra-champ
  et AND inter-champs
- TicketListRequestDto en tableaux + from_request (parse/déduplication)
- MCP idea_ticket_list aligné sur le nouveau contrat

Frontend :
- TicketListQuery.statuses/priorities
- UI de cases à cocher, toggle/clear des filtres

Tests verts : issue_store (7), app-tauri --lib (59), mcp_server (24),
issue_usecases (6), sprint_usecases (6), frontend vitest (505), npm run build (exit 0).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/features/tickets/TicketsPanel.tsx

@@ -9,12 +9,7 @@
 
 import { useState } from "react";
 
-import type {
-  Sprint,
-  TicketPriority,
-  TicketStatus,
-  TicketSummary,
-} from "@/domain";
+import type { Sprint, TicketPriority, TicketSummary } from "@/domain";
 import { Button, Input, Panel, Spinner, cn } from "@/shared";
 import { useTickets } from "./useTickets";
 import { useProjectAgents } from "./useProjectAgents";
@@ -165,45 +160,53 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
             vm.setQuery({ ...vm.query, text: e.target.value || undefined })
           }
         />
+        {/* Multi-select facets (ticket #12): OR within a facet, AND across; no
+            box ticked ⇒ that facet is unconstrained. */}
+        <fieldset
+          aria-label="filter by status"
+          className="flex flex-wrap items-center gap-x-3 gap-y-1"
+        >
+          <legend className="mr-1 text-xs font-medium text-muted">Statut</legend>
+          {TICKET_STATUSES.map((s) => (
+            <label
+              key={s}
+              className="flex cursor-pointer items-center gap-1.5 text-xs"
+            >
+              <input
+                type="checkbox"
+                aria-label={`filter status ${statusLabel(s)}`}
+                className="accent-primary"
+                checked={(vm.query.statuses ?? []).includes(s)}
+                onChange={() => vm.toggleStatus(s)}
+              />
+              <StatusBadge status={s} />
+            </label>
+          ))}
+        </fieldset>
+        <fieldset
+          aria-label="filter by priority"
+          className="flex flex-wrap items-center gap-x-3 gap-y-1"
+        >
+          <legend className="mr-1 text-xs font-medium text-muted">
+            Priorité
+          </legend>
+          {TICKET_PRIORITIES.map((p) => (
+            <label
+              key={p}
+              className="flex cursor-pointer items-center gap-1.5 text-xs"
+            >
+              <input
+                type="checkbox"
+                aria-label={`filter priority ${priorityLabel(p)}`}
+                className="accent-primary"
+                checked={(vm.query.priorities ?? []).includes(p)}
+                onChange={() => vm.togglePriority(p)}
+              />
+              <PriorityBadge priority={p} />
+            </label>
+          ))}
+        </fieldset>
         <div className="flex flex-wrap items-center gap-2">
-          <select
-            aria-label="filter by status"
-            className={selectClass}
-            value={vm.query.status ?? ""}
-            onChange={(e) =>
-              vm.setQuery({
-                ...vm.query,
-                status: (e.target.value || undefined) as TicketStatus | undefined,
-              })
-            }
-          >
-            <option value="">All statuses</option>
-            {TICKET_STATUSES.map((s) => (
-              <option key={s} value={s}>
-                {statusLabel(s)}
-              </option>
-            ))}
-          </select>
-          <select
-            aria-label="filter by priority"
-            className={selectClass}
-            value={vm.query.priority ?? ""}
-            onChange={(e) =>
-              vm.setQuery({
-                ...vm.query,
-                priority: (e.target.value || undefined) as
-                  | TicketPriority
-                  | undefined,
-              })
-            }
-          >
-            <option value="">All priorities</option>
-            {TICKET_PRIORITIES.map((p) => (
-              <option key={p} value={p}>
-                {priorityLabel(p)}
-              </option>
-            ))}
-          </select>
           <select
             aria-label="filter by assignee"
             className={selectClass}
@@ -222,6 +225,17 @@ export function TicketsPanel({ projectId, onOpen }: TicketsPanelProps) {
               </option>
             ))}
           </select>
+          {((vm.query.statuses?.length ?? 0) > 0 ||
+            (vm.query.priorities?.length ?? 0) > 0) && (
+            <Button
+              size="sm"
+              variant="ghost"
+              aria-label="clear filters"
+              onClick={() => vm.clearFacets()}
+            >
+              Effacer
+            </Button>
+          )}
         </div>
       </div>