feat: floating action button for starting tools globally

- New StartToolFAB component: fixed floating button (bottom-right) opens
  a modal with workspace selector + ToolStarter
- Added to AppShell: available on every page except mobile terminal
- Dashboard (home): removed old CreateSessionForm and 'Quick create' section,
  replaced with FAB + 'Workspaces quick access' prompt
- Sessions page: removed inline workspace selector + ToolStarter, now
  shows prompt to use the FAB
- Styles: .start-tool-fab with hover scale, shadow, mobile offset above tab bar

Quality gates: tsc --noEmit clean, pytest workspaces API (9 passed, 1 skipped)

apps/web/src/pages/sessions.tsx

@@ -6,14 +6,11 @@ import {
 	checkInstanceHealth,
 } from "../api/sessions";
 import { getUserConfig } from "../api/settings";
-import { listAllWorkspaces } from "../api/workspaces";
 import { ErrorState, LoadingState } from "../components/data-states";
 import { SessionList } from "../components/session-list";
 import { SessionCard } from "../components/session-card";
-import { ToolStarter } from "../components/tool-starter";
 import { useInstanceActions } from "../hooks/use-instance-actions";
 import type { InstanceHealth } from "../api/sessions";
-import type { Workspace } from "../types/workspace";
 
 type SessionsStatus = "loading" | "ready" | "error";
 
@@ -22,12 +19,6 @@ export const SessionsPage = () => {
 	const [sessions, setSessions] = useState<Session[]>([]);
 	const [lastSessionId, setLastSessionId] = useState<string | null>(null);
 
-	const [workspaces, setWorkspaces] = useState<Workspace[]>([]);
-	const [workspacesLoading, setWorkspacesLoading] = useState(true);
-	const [selectedWorkspace, setSelectedWorkspace] = useState<Workspace | null>(
-		null,
-	);
-
 	const [tunnelHealth, setTunnelHealth] = useState<
 		Record<string, InstanceHealth>
 	>({});
@@ -51,21 +42,6 @@ export const SessionsPage = () => {
 		void loadSessions();
 	}, [loadSessions]);
 
-	// Load workspaces for the tool-starter flow
-	useEffect(() => {
-		const load = async () => {
-			try {
-				const data = await listAllWorkspaces();
-				setWorkspaces(data);
-			} catch {
-				// ignore
-			} finally {
-				setWorkspacesLoading(false);
-			}
-		};
-		void load();
-	}, []);
-
 	const {
 		loadingSessionId,
 		dirtyDeleteSession,
@@ -123,11 +99,6 @@ export const SessionsPage = () => {
 
 	const lastSession = sessions.find((s) => s.id === lastSessionId) ?? null;
 
-	const handleToolStarted = async () => {
-		setSelectedWorkspace(null);
-		await loadSessions();
-	};
-
 	return (
 		<section className="stack sessions-page">
 			<div className="page-header">
@@ -173,71 +144,13 @@ export const SessionsPage = () => {
 						/>
 					</div>
 
-					{/* Create Session — workspace-first */}
+					{/* Create Session — use floating button */}
 					<div className="create-session-section">
 						<h2>Start New Tool</h2>
-						{workspacesLoading ? (
-							<p className="muted">Loading workspaces...</p>
-						) : workspaces.length === 0 ? (
-							<p className="muted">
-								No workspaces yet.{" "}
-								<a href="/workspaces">Create a workspace first</a>.
-							</p>
-						) : (
-							<div className="stack">
-								{!selectedWorkspace ? (
-									<div className="form-group">
-										<label htmlFor="workspace-select">
-											Select a workspace to start a tool in
-										</label>
-										<select
-											id="workspace-select"
-											value=""
-											onChange={(e) => {
-												const ws = workspaces.find(
-													(w) => w.id === e.target.value,
-												);
-												if (ws) setSelectedWorkspace(ws);
-											}}
-										>
-											<option value="">
-												Choose a workspace...
-											</option>
-											{workspaces.map((ws) => (
-												<option key={ws.id} value={ws.id}>
-													{ws.project_name} / {ws.repo_name} /{" "}
-													{ws.name}
-												</option>
-											))}
-										</select>
-									</div>
-								) : (
-									<div className="card">
-										<div className="tool-starter-header">
-											<h4>
-												{selectedWorkspace.project_name} /{" "}
-												{selectedWorkspace.repo_name} /{" "}
-												{selectedWorkspace.name}
-											</h4>
-											<button
-												className="ghost-button small"
-												onClick={() =>
-													setSelectedWorkspace(null)
-												}
-												type="button"
-											>
-												Change
-											</button>
-										</div>
-										<ToolStarter
-											workspace={selectedWorkspace}
-											onStarted={handleToolStarted}
-											onCancel={() => setSelectedWorkspace(null)}
-										/>
-									</div>
-								)}
-							</div>
-						)}
+						<p className="muted">
+							Use the floating button (bottom-right) to start a tool in any
+							workspace.
+						</p>
 					</div>
 
 					{/* Dirty Delete Confirmation Modal */}