feat: redesign Clients admin — drag-and-drop, inline edit, tags

Schema:
- Client model: add tags String[] field
- Shared types + Zod schemas updated for tags

API:
- client.create/update: accept tags array
- client.delete: with safety checks (no projects, no children)
- client.batchUpdateSortOrder: batch reorder in transaction

UI (complete redesign of ClientsAdminClient):
- Drag-and-drop reordering via @dnd-kit (sortable)
- Inline editing: click name/sortOrder to edit in-place
- Tag pills: auto-colored by hash, add/remove inline
- Tag auto-suggest from existing tags across all clients
- Sticky "Add Client" input row at top
- Search/filter by name, code, or tag
- Delete with inline confirmation
- Optimistic reorder (instant UI update)
- Full dark theme support

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/package.json

@@ -11,6 +11,9 @@
     "test:e2e": "playwright test"
   },
   "dependencies": {
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/sortable": "^10.0.0",
+    "@dnd-kit/utilities": "^3.2.2",
     "@node-rs/argon2": "^2.0.2",
     "@planarchy/api": "workspace:*",
     "@planarchy/application": "workspace:*",