feat: overhaul all 12 sector extensions with full CRUD, validation, and tests

Add shared components (ConfirmDeleteDialog, EditEntryDialog, validation utils),
enhance all 12 extension workspaces with edit/delete dialogs, input validation,
period comparisons, and new analytics features. Fix critical bugs in
ProjectBilling margin calculation and EarningsPerLiter revenue allocation.
Add pure calculation modules with 183 new tests across all extensions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

components/dashboard/DashboardNav.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { useState, useEffect, useCallback } from 'react'
+import { useState, useCallback } from 'react'
 import Link from 'next/link'
 import { usePathname, useRouter } from 'next/navigation'
 import { createClient } from '@/lib/supabase/client'
@@ -23,6 +23,7 @@ import {
   ChevronDown,
   Building2,
   FileInput,
+  Store,
 } from 'lucide-react'
 import { getExtensionDefinition } from '@/lib/extensions/sectors'
 import { resolveIcon } from '@/lib/extensions/icon-resolver'
@@ -85,10 +86,16 @@ export default function DashboardNav({ companyName, entityType, enabledExtension
     }
   }, [])
 
-  // Refresh extensions when dropdown is opened or mobile menu is opened
-  useEffect(() => {
-    if (isTillaggExpanded || isMobileMenuOpen) fetchExtensions()
-  }, [isTillaggExpanded, isMobileMenuOpen, fetchExtensions])
+  const toggleTillagg = () => {
+    const next = !isTillaggExpanded
+    setIsTillaggExpanded(next)
+    if (next) fetchExtensions()
+  }
+
+  const openMobileMenu = () => {
+    setIsMobileMenuOpen(true)
+    fetchExtensions()
+  }
 
   const handleLogout = async () => {
     await supabase.auth.signOut()
@@ -196,10 +203,31 @@ export default function DashboardNav({ companyName, entityType, enabledExtension
                 </div>
               </div>
 
+              {/* Marketplace - standalone link */}
+              <div className="mb-4">
+                <div className="space-y-px">
+                  <Link
+                    href="/extensions"
+                    className={cn(
+                      'group flex items-center px-3 py-[7px] text-[13px] transition-colors duration-150 rounded-lg',
+                      isActive('/extensions')
+                        ? 'bg-primary/8 text-foreground font-medium'
+                        : 'text-muted-foreground hover:text-foreground hover:bg-muted/40'
+                    )}
+                  >
+                    <Store className={cn(
+                      "mr-2.5 h-[15px] w-[15px] flex-shrink-0",
+                      isActive('/extensions') ? "text-primary" : "text-muted-foreground/70 group-hover:text-muted-foreground"
+                    )} />
+                    Marketplace
+                  </Link>
+                </div>
+              </div>
+
               {/* Tillägg - collapsible */}
               <div className="mb-4">
                 <button
-                  onClick={() => setIsTillaggExpanded(!isTillaggExpanded)}
+                  onClick={toggleTillagg}
                   className="w-full flex items-center justify-between px-3 mb-1.5 text-[10px] font-semibold text-muted-foreground/70 uppercase tracking-[0.08em] hover:text-muted-foreground transition-colors"
                 >
                   <span>Tillägg</span>
@@ -330,7 +358,7 @@ export default function DashboardNav({ companyName, entityType, enabledExtension
           })}
           {/* Menu button */}
           <button
-            onClick={() => setIsMobileMenuOpen(true)}
+            onClick={openMobileMenu}
             aria-label="Öppna meny"
             className="flex flex-col items-center justify-center flex-1 h-full text-xs text-muted-foreground transition-colors duration-200"
           >
@@ -426,6 +454,23 @@ export default function DashboardNav({ companyName, entityType, enabledExtension
                 })}
               </div>
 
+              {/* Marketplace */}
+              <div className="mb-4">
+                <Link
+                  href="/extensions"
+                  onClick={closeMobileMenu}
+                  className={cn(
+                    'flex items-center gap-3 px-3 py-2.5 rounded-lg transition-colors',
+                    isActive('/extensions')
+                      ? 'bg-primary/10 text-primary font-medium'
+                      : 'text-muted-foreground hover:bg-secondary/50 hover:text-foreground'
+                  )}
+                >
+                  <Store className="h-5 w-5" />
+                  Marketplace
+                </Link>
+              </div>
+
               {/* Tillägg */}
               <div className="mb-4">
                 <p className="px-3 py-2 text-xs font-medium text-muted-foreground uppercase tracking-wider">