docs(cli): add tts command to --help and CLI docs

CLAUDE.md

@@ -72,7 +72,9 @@ When adding a new CLI command:
 1. Define the command in `packages/cli/src/commands/<name>.ts` using `defineCommand` from citty
 2. **Export `examples`** in the same file — `export const examples: Example[] = [...]` (import `Example` from `./_examples.js`). These are displayed by `--help`.
 3. Register it in `packages/cli/src/cli.ts` under `subCommands` (lazy-loaded)
-4. Validate by running `npx tsx packages/cli/src/cli.ts <name> --help` and verifying the examples section appears
+4. **Add to help groups** in `packages/cli/src/help.ts` — add the command name and description to the appropriate `GROUPS` entry. Without this, the command won't appear in `hyperframes --help` even though it works.
+5. **Document it** in `docs/packages/cli.mdx` — add a section with usage examples and flags.
+6. Validate by running `npx tsx packages/cli/src/cli.ts --help` (command appears in the list) and `npx tsx packages/cli/src/cli.ts <name> --help` (examples appear).
 
 ## Key Concepts
 

docs/packages/cli.mdx

@@ -226,6 +226,42 @@ This is suppressed in CI environments, non-TTY shells, and when `HYPERFRAMES_NO_
     <Tip>
       For music or noisy audio, use `--model medium.en` for better accuracy. For the best results with production content, transcribe via the OpenAI or Groq Whisper API and import the JSON.
     </Tip>
+
+    ### `tts`
+
+    Generate speech audio from text using a local AI model (Kokoro-82M). No API key required — runs entirely on-device.
+
+    ```bash
+    # Generate speech from text
+    npx hyperframes tts "Welcome to HyperFrames"
+
+    # Choose a voice
+    npx hyperframes tts "Hello world" --voice am_adam
+
+    # Save to a specific file
+    npx hyperframes tts "Intro" --voice bf_emma --output narration.wav
+
+    # Adjust speech speed
+    npx hyperframes tts "Slow and clear" --speed 0.8
+
+    # Read text from a file
+    npx hyperframes tts script.txt
+
+    # List available voices
+    npx hyperframes tts --list
+    ```
+
+    | Flag | Description |
+    |------|-------------|
+    | `--output, -o` | Output file path (default: `speech.wav` in current directory) |
+    | `--voice, -v` | Voice ID (run `--list` to see options) |
+    | `--speed, -s` | Speech speed multiplier (default: 1.0) |
+    | `--list` | List available voices and exit |
+    | `--json` | Output result as JSON |
+
+    <Tip>
+      Combine `tts` with `transcribe` to generate narration and word-level timestamps for captions in a single workflow: generate the audio with `tts`, then transcribe the output with `transcribe` to get word-level timing.
+    </Tip>
   </Tab>
   <Tab title="Preview">
     ### `preview`

packages/cli/src/help.ts

@@ -53,6 +53,7 @@ const GROUPS: Group[] = [
         "transcribe",
         "Transcribe audio/video to word-level timestamps, or import an existing transcript",
       ],
+      ["tts", "Generate speech audio from text using a local AI model (Kokoro-82M)"],
     ],
   },
   {