refactor: onboarding, mobile nav, remove maintenance flows

- Onboarding steps guide toward copilot usage, not flow building
- Mobile nav updated to match sidebar (Session History, Guided Flows)
- Remove Step Library from mobile nav
- Remove Maintenance from flow type filter tabs
- Remove Maintenance badge from all tree views (grid, list, table)
- Remove Maintenance create option from CreateFlowDropdown
- Add copilot-first dashboard plan and solutions library spec docs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/common/CreateFlowDropdown.tsx

@@ -137,24 +137,12 @@ export function CreateFlowDropdown({
 
             <div className="my-1 border-t border-border" />
 
-            {/* Maintenance */}
-            <Link
-              to="/flows/new?type=maintenance"
-              onClick={() => setShowMenu(false)}
-              className="flex items-center gap-3 rounded-md px-3 py-2.5 text-sm text-foreground hover:bg-accent"
-            >
-              <Wrench className="h-4 w-4 text-amber-400" />
-              <div className="flex-1">
-                <div className="font-medium">Maintenance Flow</div>
-                <div className="text-xs text-muted-foreground">Scheduled multi-target tasks</div>
-              </div>
-            </Link>
             {aiEnabled && (
               <button
                 type="button"
                 onClick={() => {
                   setShowMenu(false)
-                  setAiPromptFlowType('maintenance')
+                  setAiPromptFlowType('procedural')
                   setAiPromptOpen(true)
                 }}
                 className="flex w-full items-center gap-3 rounded-md px-3 py-2 text-sm text-foreground hover:bg-accent"