Add cancel, history, revert, and quality-of-life features

UX

- Add elapsed-time counter and Cancel button to in-flight generations,
  wired through AbortController so partial responses are discarded
  cleanly. The cancel action is available from both the input panel
  and the results header.
- Add a Recent generations panel below the input. The last 6 successful
  generations are saved to localStorage; one click reloads both the
  input fields and the generated assets.
- Add a Revert button to every editable card. It appears the moment
  the current value diverges from the last generated value and restores
  the field with a single click.
- Add an Empty state to the right panel with a friendly hint pointing
  at the Generate button and the Settings page.
- Add a 'Try an example' button that fills the input with a random
  starter idea (idea + mood + vocals).
- Add Cmd/Ctrl+Enter as a keyboard shortcut to generate.
- Add a Footer with project info and a privacy reminder.
- Add a 'Clear saved key' button to the Settings page so the user can
  remove the API key without overwriting it.

Bug fix

- Settings > Test Connection used to save the in-progress form values
  to localStorage before testing. It now uses the in-memory candidate
  config, so failed tests don't pollute the saved config.

Code quality

- Extract the duplicated useAutoHeight hook to src/lib/useAutoHeight.ts.
- Extract a useElapsed hook for the loading timer.
- Move InputValues into src/lib/types.ts (was duplicated in
  InputPanel.tsx) and add SECTION_LABELS, replacing the humanizeSection
  switch in HomePage.
- Centralize the filename sanitization: HomePage now calls
  sanitizeFilename from zip.ts instead of duplicating the regex.
- Add previewConfig / testConnectionWithConfig helpers to llm.ts to
  support in-memory connection tests.

README.md

@@ -11,6 +11,18 @@ OpenAI-compatible `/chat/completions` endpoint, using credentials that you
 paste into the Settings page. Those credentials are kept in this browser's
 `localStorage`.
 
+## Features
+
+- 🎵 **All 5 Suno assets in one click** — titles, lyrics, style, video prompts, YouTube description
+- ✏️ **Inline editing** — every generated field is editable; revert any edit with one click
+- 🔄 **Per-section regeneration** — regenerate just one section; the rest of the song is passed as context for consistency
+- ⏱ **Elapsed-time counter** + ❌ **Cancel** button for long generations
+- 🕘 **Recent generations** — last 6 are kept in localStorage; one click to reload
+- ⌨️ **Keyboard shortcut** — `Cmd/Ctrl + Enter` to generate
+- 🎲 **Try an example** — fill the input with a random sample idea
+- 🌗 **Dark / light mode** — toggle in the header, persisted
+- 💾 **Standalone** — no backend, no signup, no telemetry
+
 ## Tech stack
 
 - React 18 + TypeScript + Vite
@@ -27,15 +39,29 @@ MelodyMuse/
 │   ├── main.tsx
 │   ├── index.css                # Tailwind layers + design-system components
 │   ├── components/              # UI building blocks
-│   │   └── cards/               # The five result cards
+│   │   ├── cards/               # The five result cards
+│   │   ├── ConfigBanner.tsx
+│   │   ├── CopyButton.tsx
+│   │   ├── EqualizerIcon.tsx
+│   │   ├── Footer.tsx
+│   │   ├── HistoryPanel.tsx
+│   │   ├── InputPanel.tsx
+│   │   ├── ResultCard.tsx
+│   │   ├── ResultsPanel.tsx
+│   │   ├── SkeletonCard.tsx
+│   │   ├── StickyZipBar.tsx
+│   │   └── ThemeToggle.tsx
 │   ├── pages/                   # HomePage, SettingsPage
 │   ├── lib/
+│   │   ├── history.ts           # recent-generations persistence
 │   │   ├── llm.ts               # direct fetch → provider, JSON extraction, config persistence
 │   │   ├── prompts.ts           # system + user prompt construction
-│   │   ├── types.ts             # shared TypeScript types
-│   │   ├── zip.ts               # JSZip layout
 │   │   ├── theme.ts             # dark/light mode
-│   │   └── toast.tsx            # toast context
+│   │   ├── toast.tsx            # toast context
+│   │   ├── types.ts             # shared TypeScript types + SECTION_LABELS
+│   │   ├── useAutoHeight.ts     # shared textarea auto-grow hook
+│   │   ├── useElapsed.ts        # shared "X seconds elapsed" hook
+│   │   └── zip.ts               # JSZip layout
 │   └── vite-env.d.ts
 ├── public/favicon.svg
 ├── index.html
@@ -68,10 +94,11 @@ MelodyMuse/
    - **Model Name** — e.g. `MiniMax-M3`
 
    Click **Save Configuration**, then **Test Connection** to confirm
-   everything is wired up.
+   everything is wired up. **Test Connection** uses your unsaved form
+   values — your changes are only persisted when you click **Save**.
 
 4. **Generate**. Return to the home page, type a music idea, click
-   **Generate Song Assets**.
+   **Generate Song Assets** (or press `Cmd/Ctrl + Enter`).
 
 ## Build for production
 
@@ -112,8 +139,11 @@ The configured endpoint must expose an OpenAI-compatible
 
 - The API key is held in `localStorage` and is only sent to the endpoint you
   configure. No analytics, no telemetry, no third-party calls.
-- The `MelodyMuse-config` localStorage key contains your endpoint URL, model
-  name, and key. You can clear it at any time from your browser's devtools
+- Three localStorage keys are used:
+  - `melodymuse-config` — `{ api_endpoint, api_key, model_name }`
+  - `melodymuse-history` — the last 6 generations (input + assets)
+  - `melodymuse-theme` — `'dark' | 'light'`
+- You can clear them at any time from your browser's devtools
   (Application → Local Storage).
 
 ## License