feat: add project reset functionality with quick and full reset options

Add the ability to reset a project to its initial state with two options:
- Quick Reset: Clears features.db, assistant.db, and settings files while
  preserving app spec and prompts
- Full Reset: Deletes everything including prompts directory, triggering
  the setup wizard for project reconfiguration

Backend changes:
- Add POST /{name}/reset endpoint to projects router with full_reset query param
- Validate agent lock file to prevent reset while agent is running (409 Conflict)
- Dispose database engines before deleting files to release Windows file locks
- Add engine caching to api/database.py for better connection management
- Add dispose_engine() functions to both database modules
- Delete WAL mode journal files (*.db-wal, *.db-shm) during reset

Frontend changes:
- Add ResetProjectModal component with toggle between Quick/Full reset modes
- Add ProjectSetupRequired component shown when has_spec is false
- Add resetProject API function and useResetProject React Query hook
- Integrate reset button in header (disabled when agent running)
- Add 'R' keyboard shortcut to open reset modal
- Show ProjectSetupRequired when project needs setup after full reset

This implements the feature from PR #4 directly on master to avoid merge
conflicts.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ui/src/App.tsx

@@ -26,8 +26,10 @@ import { ViewToggle, type ViewMode } from './components/ViewToggle'
 import { DependencyGraph } from './components/DependencyGraph'
 import { KeyboardShortcutsHelp } from './components/KeyboardShortcutsHelp'
 import { ThemeSelector } from './components/ThemeSelector'
+import { ResetProjectModal } from './components/ResetProjectModal'
+import { ProjectSetupRequired } from './components/ProjectSetupRequired'
 import { getDependencyGraph } from './lib/api'
-import { Loader2, Settings, Moon, Sun } from 'lucide-react'
+import { Loader2, Settings, Moon, Sun, RotateCcw } from 'lucide-react'
 import type { Feature } from './lib/types'
 import { Button } from '@/components/ui/button'
 import { Card, CardContent } from '@/components/ui/card'
@@ -59,6 +61,7 @@ function App() {
   const [showSettings, setShowSettings] = useState(false)
   const [showKeyboardHelp, setShowKeyboardHelp] = useState(false)
   const [isSpecCreating, setIsSpecCreating] = useState(false)
+  const [showResetModal, setShowResetModal] = useState(false)
   const [showSpecChat, setShowSpecChat] = useState(false)  // For "Create Spec" button in empty kanban
   const [viewMode, setViewMode] = useState<ViewMode>(() => {
     try {
@@ -203,10 +206,18 @@ function App() {
         setShowKeyboardHelp(true)
       }
 
+      // R : Open reset modal (when project selected and agent not running)
+      if ((e.key === 'r' || e.key === 'R') && selectedProject && wsState.agentStatus !== 'running') {
+        e.preventDefault()
+        setShowResetModal(true)
+      }
+
       // Escape : Close modals
       if (e.key === 'Escape') {
         if (showKeyboardHelp) {
           setShowKeyboardHelp(false)
+        } else if (showResetModal) {
+          setShowResetModal(false)
         } else if (showExpandProject) {
           setShowExpandProject(false)
         } else if (showSettings) {
@@ -225,7 +236,7 @@ function App() {
 
     window.addEventListener('keydown', handleKeyDown)
     return () => window.removeEventListener('keydown', handleKeyDown)
-  }, [selectedProject, showAddFeature, showExpandProject, selectedFeature, debugOpen, debugActiveTab, assistantOpen, features, showSettings, showKeyboardHelp, isSpecCreating, viewMode])
+  }, [selectedProject, showAddFeature, showExpandProject, selectedFeature, debugOpen, debugActiveTab, assistantOpen, features, showSettings, showKeyboardHelp, isSpecCreating, viewMode, showResetModal, wsState.agentStatus])
 
   // Combine WebSocket progress with feature data
   const progress = wsState.progress.total > 0 ? wsState.progress : {
@@ -287,6 +298,17 @@ function App() {
                     <Settings size={18} />
                   </Button>
 
+                  <Button
+                    onClick={() => setShowResetModal(true)}
+                    variant="outline"
+                    size="sm"
+                    title="Reset Project (R)"
+                    aria-label="Reset Project"
+                    disabled={wsState.agentStatus === 'running'}
+                  >
+                    <RotateCcw size={18} />
+                  </Button>
+
                   {/* Ollama Mode Indicator */}
                   {settings?.ollama_mode && (
                     <div
@@ -346,6 +368,16 @@ function App() {
               Select a project from the dropdown above or create a new one to get started.
             </p>
           </div>
+        ) : !hasSpec ? (
+          <ProjectSetupRequired
+            projectName={selectedProject}
+            projectPath={selectedProjectData?.path}
+            onCreateWithClaude={() => setShowSpecChat(true)}
+            onEditManually={() => {
+              // Open debug panel for the user to see the project path
+              setDebugOpen(true)
+            }}
+          />
         ) : (
           <div className="space-y-8">
             {/* Progress Dashboard */}
@@ -512,6 +544,21 @@ function App() {
       {/* Keyboard Shortcuts Help */}
       <KeyboardShortcutsHelp isOpen={showKeyboardHelp} onClose={() => setShowKeyboardHelp(false)} />
 
+      {/* Reset Project Modal */}
+      {showResetModal && selectedProject && (
+        <ResetProjectModal
+          isOpen={showResetModal}
+          projectName={selectedProject}
+          onClose={() => setShowResetModal(false)}
+          onResetComplete={(wasFullReset) => {
+            // If full reset, the spec was deleted - show spec creation chat
+            if (wasFullReset) {
+              setShowSpecChat(true)
+            }
+          }}
+        />
+      )}
+
       {/* Celebration Overlay - shows when a feature is completed by an agent */}
       {wsState.celebration && (
         <CelebrationOverlay