feat(frontend): tickets/sprints surface for the web workspace (#86 lot 2)

Adds a Live/Tickets/Sprints tab navigation to WebWorkspace after a project
is opened — a mobile-first adaptation, not a port of the desktop docks/
floating windows, per carnet #86. The web-server transport (17 ticket_*/
sprint_* commands) and the HttpTicketGateway were already wired (lot 1 +
pre-existing gateway code); this lot is UI only.

- Tickets tab: search/filters, list grouped by sprint, create screen,
  detail view with stacked accordion sections (Résumé/Statut et priorité/
  Carnet open by default; Agents assignés/Liens/Zone dangereuse collapsed),
  delete confirmation, optimistic-concurrency conflict banner.
- Sprints tab: create/rename/reorder (Monter/Descendre)/delete with
  confirmation, add tickets via a mobile full-screen ticket picker (never
  a small desktop modal), "Voir tickets" filters the Tickets tab to one
  sprint.
- Reuses the transport-neutral hooks as-is (useTickets, useTicketDetail,
  useTicketSearch) — only presentation and copy are web-specific, in
  French per decision #78 (new local label module, not a reuse of the
  English desktop ticketMeta labels).
- Workaround: `list_agents` isn't in the web-server allowlist, so agent
  names/assignment options are derived from `get_project_work_state`
  (already used by the Live tab) instead of the desktop's useProjectAgents.

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

frontend/src/features/web/tickets/WebTicketCreate.tsx

@@ -0,0 +1,141 @@
+/**
+ * Ticket creation screen for the web workspace (ticket #86) — replaces the list
+ * in the column (no inline permanent form, no desktop popup), per carnet #86.
+ *
+ * Short form: Titre (required) / Priorité / Sprint / Description (optional).
+ * On success the caller opens the created ticket's detail so the user can
+ * complete carnet/assignments/links right away.
+ */
+
+import { useState } from "react";
+
+import type { CreateTicketInput } from "@/ports";
+import type { Sprint, TicketPriority } from "@/domain";
+import { Button, Input, Panel, cn } from "@/shared";
+import { TICKET_PRIORITIES } from "@/features/tickets";
+import { webPriorityLabel } from "./webTicketLabels";
+
+const selectClass = cn(
+  "h-9 rounded-md bg-raised px-3 text-sm text-content",
+  "border border-border outline-none transition-colors",
+  "focus:border-primary disabled:cursor-not-allowed disabled:opacity-50",
+);
+
+const textareaClass = cn(
+  "w-full rounded-md bg-raised p-3 text-sm text-content",
+  "border border-border outline-none transition-colors",
+  "focus:border-primary disabled:cursor-not-allowed disabled:opacity-50",
+);
+
+export interface WebTicketCreateProps {
+  sprints: Sprint[];
+  busy: boolean;
+  error: string | null;
+  onCancel: () => void;
+  onCreate: (input: CreateTicketInput, sprintId: string | null) => Promise<void>;
+}
+
+export function WebTicketCreate({ sprints, busy, error, onCancel, onCreate }: WebTicketCreateProps) {
+  const [title, setTitle] = useState("");
+  const [description, setDescription] = useState("");
+  const [priority, setPriority] = useState<TicketPriority>("medium");
+  const [sprintId, setSprintId] = useState<string>("");
+
+  async function submit(e: React.FormEvent) {
+    e.preventDefault();
+    const trimmed = title.trim();
+    if (!trimmed) return;
+    await onCreate(
+      {
+        title: trimmed,
+        priority,
+        ...(description.trim() ? { description: description.trim() } : {}),
+      },
+      sprintId || null,
+    );
+  }
+
+  return (
+    <Panel
+      title="Nouveau ticket"
+      actions={
+        <Button size="sm" variant="ghost" onClick={onCancel}>
+          Annuler
+        </Button>
+      }
+    >
+      {error && (
+        <p role="alert" className="mb-3 rounded-md border border-danger/40 bg-danger/10 px-3 py-2 text-sm text-danger">
+          {error}
+        </p>
+      )}
+      <form onSubmit={submit} className="flex flex-col gap-3">
+        <label className="flex flex-col gap-1">
+          <span className="text-xs font-medium text-muted">Titre</span>
+          <Input
+            aria-label="Titre"
+            value={title}
+            onChange={(e) => setTitle(e.target.value)}
+            disabled={busy}
+            autoFocus
+          />
+        </label>
+
+        <label className="flex flex-col gap-1">
+          <span className="text-xs font-medium text-muted">Priorité</span>
+          <select
+            aria-label="Priorité"
+            className={selectClass}
+            value={priority}
+            disabled={busy}
+            onChange={(e) => setPriority(e.target.value as TicketPriority)}
+          >
+            {TICKET_PRIORITIES.map((p) => (
+              <option key={p} value={p}>
+                {webPriorityLabel(p)}
+              </option>
+            ))}
+          </select>
+        </label>
+
+        <label className="flex flex-col gap-1">
+          <span className="text-xs font-medium text-muted">Sprint</span>
+          <select
+            aria-label="Sprint"
+            className={selectClass}
+            value={sprintId}
+            disabled={busy}
+            onChange={(e) => setSprintId(e.target.value)}
+          >
+            <option value="">Sans sprint</option>
+            {sprints.map((s) => (
+              <option key={s.id} value={s.id}>
+                {s.name}
+              </option>
+            ))}
+          </select>
+        </label>
+
+        <label className="flex flex-col gap-1">
+          <span className="text-xs font-medium text-muted">Description</span>
+          <textarea
+            aria-label="Description"
+            className={cn(textareaClass, "min-h-20")}
+            value={description}
+            onChange={(e) => setDescription(e.target.value)}
+            disabled={busy}
+          />
+        </label>
+
+        <div className="flex justify-end gap-2 pt-1">
+          <Button type="button" variant="ghost" size="sm" disabled={busy} onClick={onCancel}>
+            Annuler
+          </Button>
+          <Button type="submit" size="sm" disabled={!title.trim() || busy} loading={busy}>
+            Créer
+          </Button>
+        </div>
+      </form>
+    </Panel>
+  );
+}