feat: Add comprehensive keyboard shortcuts system for video editor

- Implement industry-standard video editing shortcuts (Space, J/K/L, arrows)
- Add playback controls: Space (play/pause), J/K/L (rewind/pause/forward)
- Add navigation: arrow keys (frame stepping), Shift+arrows (5s jumps), Home/End
- Add editing shortcuts: S (split at playhead), N (toggle snapping)
- Add selection shortcuts: Ctrl/Cmd+A (select all), Ctrl/Cmd+D (duplicate)
- Add keyboard shortcuts help dialog with categorized shortcuts display
- Integrate help button in editor header for discoverability
- Add TypeScript type declarations for better development experience
- Fix Docker build environment variable validation issues

All shortcuts follow professional video editing standards (Avid/Premiere/Final Cut).
Context-aware shortcuts that don't interfere with text input fields.
Toast notifications provide user feedback for better UX.

1 files changed, 220 insertions, 0 deletions

diff --git a/apps/web/src/components/keyboard-shortcuts-help.tsx b/apps/web/src/components/keyboard-shortcuts-help.tsx
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+++ b/apps/web/src/components/keyboard-shortcuts-help.tsx
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+"use client";
+
+import { useState } from "react";
+import { Button } from "./ui/button";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogHeader,
+  DialogTitle,
+  DialogTrigger,
+} from "./ui/dialog";
+import { Badge } from "./ui/badge";
+import { Keyboard, Play, Pause, SkipBack, SkipForward } from "lucide-react";
+
+interface Shortcut {
+  keys: string[];
+  description: string;
+  category: string;
+  icon?: React.ReactNode;
+}
+
+const shortcuts: Shortcut[] = [
+  // Playback Controls
+  {
+    keys: ["Space"],
+    description: "Play/Pause",
+    category: "Playback",
+    icon: <Play className="w-3 h-3" />
+  },
+  {
+    keys: ["J"],
+    description: "Rewind 1 second",
+    category: "Playback",
+    icon: <SkipBack className="w-3 h-3" />
+  },
+  {
+    keys: ["K"],
+    description: "Play/Pause (alternative)",
+    category: "Playback",
+    icon: <Pause className="w-3 h-3" />
+  },
+  {
+    keys: ["L"],
+    description: "Fast forward 1 second",
+    category: "Playback",
+    icon: <SkipForward className="w-3 h-3" />
+  },
+  
+  // Navigation
+  {
+    keys: ["←"],
+    description: "Frame step backward",
+    category: "Navigation"
+  },
+  {
+    keys: ["→"],
+    description: "Frame step forward",
+    category: "Navigation"
+  },
+  {
+    keys: ["Shift", "←"],
+    description: "Jump back 5 seconds",
+    category: "Navigation"
+  },
+  {
+    keys: ["Shift", "→"],
+    description: "Jump forward 5 seconds",
+    category: "Navigation"
+  },
+  {
+    keys: ["Home"],
+    description: "Go to timeline start",
+    category: "Navigation"
+  },
+  {
+    keys: ["End"],
+    description: "Go to timeline end",
+    category: "Navigation"
+  },
+
+  // Editing
+  {
+    keys: ["S"],
+    description: "Split element at playhead",
+    category: "Editing"
+  },
+  {
+    keys: ["Delete", "Backspace"],
+    description: "Delete selected elements",
+    category: "Editing"
+  },
+  {
+    keys: ["N"],
+    description: "Toggle snapping",
+    category: "Editing"
+  },
+
+  // Selection & Organization
+  {
+    keys: ["Cmd", "A"],
+    description: "Select all elements",
+    category: "Selection"
+  },
+  {
+    keys: ["Cmd", "D"],
+    description: "Duplicate selected element",
+    category: "Selection"
+  },
+
+  // History
+  {
+    keys: ["Cmd", "Z"],
+    description: "Undo",
+    category: "History"
+  },
+  {
+    keys: ["Cmd", "Shift", "Z"],
+    description: "Redo",
+    category: "History"
+  },
+  {
+    keys: ["Cmd", "Y"],
+    description: "Redo (alternative)",
+    category: "History"
+  }
+];
+
+const KeyBadge = ({ keyName }: { keyName: string }) => {
+  // Replace common key names with symbols
+  const displayKey = keyName
+    .replace("Cmd", "⌘")
+    .replace("Shift", "⇧")
+    .replace("←", "◀")
+    .replace("→", "▶")
+    .replace("Space", "⎵");
+
+  return (
+    <Badge variant="secondary" className="font-mono text-xs px-2 py-1">
+      {displayKey}
+    </Badge>
+  );
+};
+
+const ShortcutItem = ({ shortcut }: { shortcut: Shortcut }) => (
+  <div className="flex items-center justify-between py-2 px-3 rounded-lg hover:bg-muted/50">
+    <div className="flex items-center gap-3">
+      {shortcut.icon && (
+        <div className="text-muted-foreground">{shortcut.icon}</div>
+      )}
+      <span className="text-sm">{shortcut.description}</span>
+    </div>
+    <div className="flex items-center gap-1">
+      {shortcut.keys.map((key, index) => (
+        <div key={index} className="flex items-center gap-1">
+          <KeyBadge keyName={key} />
+          {index < shortcut.keys.length - 1 && (
+            <span className="text-xs text-muted-foreground">+</span>
+          )}
+        </div>
+      ))}
+    </div>
+  </div>
+);
+
+export const KeyboardShortcutsHelp = () => {
+  const [open, setOpen] = useState(false);
+
+  const categories = Array.from(new Set(shortcuts.map(s => s.category)));
+
+  return (
+    <Dialog open={open} onOpenChange={setOpen}>
+      <DialogTrigger asChild>
+        <Button variant="ghost" size="sm" className="gap-2">
+          <Keyboard className="w-4 h-4" />
+          Shortcuts
+        </Button>
+      </DialogTrigger>
+      <DialogContent className="max-w-2xl max-h-[80vh] overflow-y-auto">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2">
+            <Keyboard className="w-5 h-5" />
+            Keyboard Shortcuts
+          </DialogTitle>
+          <DialogDescription>
+            Speed up your video editing workflow with these keyboard shortcuts.
+            Most shortcuts work when the timeline is focused.
+          </DialogDescription>
+        </DialogHeader>
+        
+        <div className="space-y-6">
+          {categories.map(category => (
+            <div key={category}>
+              <h3 className="font-semibold text-sm text-muted-foreground uppercase tracking-wide mb-3">
+                {category}
+              </h3>
+              <div className="space-y-1">
+                {shortcuts
+                  .filter(shortcut => shortcut.category === category)
+                  .map((shortcut, index) => (
+                    <ShortcutItem key={index} shortcut={shortcut} />
+                  ))}
+              </div>
+            </div>
+          ))}
+        </div>
+
+        <div className="mt-6 p-4 bg-muted/30 rounded-lg">
+          <h4 className="font-medium text-sm mb-2">Tips:</h4>
+          <ul className="text-sm text-muted-foreground space-y-1">
+            <li>• Shortcuts work when the editor is focused (not typing in inputs)</li>
+            <li>• J/K/L are industry-standard video editing shortcuts</li>
+            <li>• Use arrow keys for frame-perfect positioning</li>
+            <li>• Hold Shift with arrow keys for larger jumps</li>
+          </ul>
+        </div>
+      </DialogContent>
+    </Dialog>
+  );
+}; 
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