feat: UI design system - sidebar layout, workspace system, and shell redesign (#77)

* feat: add workspace system and sidebar layout (UI design system Phase A+B)

Backend: Workspace model, migration (036), schemas, CRUD API endpoints.
Adds workspace_id to trees and categories, seeds 4 default workspaces
per account, auto-assigns existing trees by tree_type.

Frontend: Complete AppLayout rewrite from top-nav to CSS Grid shell
with persistent sidebar + topbar. New components: WorkspaceSwitcher,
NavItem, CategoryList, TagCloud, TopBar, Sidebar. Dashboard components:
QuickStats, FiltersBar, SectionGroup, TreeListItem, SessionsPanel.
WorkspaceStore with localStorage persistence.

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

* feat: add command palette search, dashboard rewrite, and shell height fixes (Phase C)

- Add ⌘K command palette with debounced search across flows and sessions
- Rewrite QuickStartPage as dashboard with stats, filters, sessions panel
- Fix h-[calc(100vh-4rem)] → h-full across all pages for CSS Grid shell
- Add active session count badge to sidebar Sessions nav item

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

* feat: add sidebar collapse, category/tag filtering, and workspace CRUD (Phase D)

- Sidebar collapse/expand toggle with icon-only rail mode (persisted)
- Sidebar category/tag clicks navigate to /trees with URL params
- TreeLibraryPage syncs filters from URL search params bidirectionally
- Workspace create modal with icon picker and auto-slug generation
- TopBar logo adapts to collapsed sidebar state

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

* feat: add Quick Launch modal with actions and recent flows

- Zap button opens Quick Launch with create/navigate shortcuts
- Shows recent flows for quick session start
- Keyboard navigation support (arrows + enter)

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

* feat: add activity notifications panel with session feed

- Bell icon shows dot indicator for recent activity
- Dropdown panel shows recent sessions with status icons
- Links to session detail and sessions list page

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

* feat: remove workspace system, add pinned flows and label renames

Replace workspace system with pinned flows API (pin/unpin/list/reorder).
Rename user-facing labels: Tree→Flow, Procedure→Project. Add sidebar
nav sub-items for flow type filtering. Remove 11 workspace files,
add migrations 037-038, clean all workspace references.

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

* fix: collapsed sidebar layout scaling and toggle button size

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

* refactor: migrate auth pages to new design system

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

* refactor: migrate TreeLibraryPage to new design system

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

* refactor: migrate session pages to new design system

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

* refactor: migrate TreeEditorPage to new design system

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

* refactor: migrate TreeNavigationPage to new design system

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

* refactor: migrate session sharing components to new design system

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

* chore: remove workspace dropdown animation (dead code)

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

* refactor: migrate common components to new design system

Migrate 15 components from monochrome glass-card design to purple gradient
accent design system tokens (bg-card, border-border, text-foreground,
bg-gradient-brand, etc.)

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

* refactor: migrate procedural and step library components to new design system

Migrate 10 components from monochrome glass-card design to purple gradient
accent design system tokens.

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

* refactor: migrate admin pages and components to new design system

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

* refactor: migrate remaining pages to new design system

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

* refactor: migrate remaining components to new design system

Migrates 38 files: tree-editor forms, session modals, step library,
common components, library views, tree preview, and misc UI to use
design tokens (bg-card, border-border, text-foreground, bg-accent,
bg-gradient-brand) replacing old monochrome patterns.

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

* fix: keep brand text visible on sidebar collapse, hide sub-items until hover

- TopBar: always show "ResolutionFlow" text regardless of sidebar state
- NavItem: sub-items (Troubleshooting, Projects) hidden by default,
  revealed on hover or when a child route is active

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -24,10 +24,10 @@
 - **Logo:** Inline SVG in `BrandLogo.tsx` (decision-tree icon with gradient). Wordmark: "Resolution" in white + "Flow" in `text-gradient-brand`
 - **Brand assets:** `brand-assets/` (source SVGs + brand-guide.html), `frontend/src/assets/brand/` (app assets), `frontend/public/icons/` (favicon)
 - **CSS utilities:** `text-gradient-brand`, `bg-gradient-brand`, `bg-gradient-brand-hover` (defined in `tailwind.config.js` and `index.css`)
-- **Layout:** App shell with persistent sidebar + top bar + main workspace (CSS Grid). See [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md)
-- **Workspace system:** Top-level context switcher (Troubleshooting, Procedures, Policies, Finance). Sidebar categories, tags, stats, and content adapt per workspace. See [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md)
+- **Layout:** App shell with persistent sidebar + top bar + main content (CSS Grid). See [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md)
+- **Navigation:** Sidebar nav with type sub-items (All Flows → Troubleshooting / Projects). Pinned flows section for quick access. NO workspace switcher. See [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md)
+- **Terminology:** User-facing label is "Flows" (not "Trees"). Procedural flows are called "Projects" in the UI. `tree_type` column values unchanged in DB.
 - **Rebrand guide:** [REBRAND-IMPLEMENTATION-GUIDE.md](REBRAND-IMPLEMENTATION-GUIDE.md)
-- **Interactive mockup:** `docs/mockups/resolutionflow-workspaces-mockup.html` (open in browser for visual reference)
 
 **Component styling rules:**
 - Primary buttons: `bg-gradient-brand` with `shadow-lg shadow-primary/20`, hover lifts with stronger shadow
@@ -40,7 +40,7 @@
 - Cards: `bg-card border-border rounded-xl`, hover brightens border
 - Section labels: `font-label text-[0.6875rem] uppercase tracking-wide text-muted-foreground`
 
-When adding new pages/components: use "ResolutionFlow" branding, purple gradient accent theme, `bg-card` containers, `text-foreground`/`text-muted-foreground` hierarchy. Primary actions use `bg-gradient-brand`. Pages render inside the app shell (CSS Grid: topbar + sidebar + main). Reference [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md) for layout patterns, workspace context, and component specs.
+When adding new pages/components: use "ResolutionFlow" branding, purple gradient accent theme, `bg-card` containers, `text-foreground`/`text-muted-foreground` hierarchy. Primary actions use `bg-gradient-brand`. Pages render inside the app shell (CSS Grid: topbar + sidebar + main). Use "Flows" not "Trees" in all user-facing text; use "Projects" not "Procedures" for procedural flows. Reference [UI-DESIGN-SYSTEM.md](UI-DESIGN-SYSTEM.md) for layout patterns, navigation, and component specs.
 
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