README: trim to brief front page + retake themed screenshots (#106)

- Cut Admin walkthrough and API curl block to one-liners pointing at docs
- Keep Configuration table, features, Get Started, doc links
- Retake all screenshots against current UI, one theme each:
  /new midnight, /history pastel-lavender, paste view pastel-peach,
  /mine pastel-cloud; remove superseded stale previews

README.md

@@ -40,8 +40,8 @@ The SQLite database lives in the `/data` volume inside the container.
 
 | | |
 |---|---|
-| ![Editor](docs/palette-previews/pastel-lavender-new.png) | ![Paste view](docs/palette-previews/pastel-lavender-paste.png) |
+| ![Editor in midnight](docs/palette-previews/midnight-new.png) | ![Paste view in pastel-peach](docs/palette-previews/pastel-peach-paste.png) |
-| ![History](docs/palette-previews/midnight-history.png) | |
+| ![History in pastel-lavender](docs/palette-previews/pastel-lavender-history.png) | ![Saved in pastel-cloud](docs/palette-previews/pastel-cloud-mine.png) |
 
 ## Configuration
 
@@ -53,31 +53,19 @@ The SQLite database lives in the `/data` volume inside the container.
 | `PALETTE_MAX_ITEM` | `26214400` | Max can item size in bytes (25 MB) |
 | `PALETTE_ADMIN_KEY` | generated | Admin key; if unset a 32-char hex key is generated and persisted to `<db-dir>/admin-key` (0600) |
 
-### Admin
+An `/admin` page exists for runtime settings, protected by a key set at
-
+install (`PALETTE_ADMIN_KEY` env var) and resettable locally — see
-`GET /admin` serves the admin page. Enter the admin key there — it is stored in
+[docs/API.md](docs/API.md) and [docs/design/](docs/design/) for details.
-`sessionStorage` (never a cookie) and sent as the `X-Admin-Key` header on
-`GET`/`POST /admin/api/settings`.
-
-The admin API reads/sets: rate-limit burst, rate-limit refill per minute, max
-content bytes, default expiry, custom URL reservation days, and the burn
-viewer window (minutes). All admin access attempts are logged.
-
-```bash
-./palette --reset-admin-key   # regenerate the admin key and print it
-```
 
 ## API
 
-Create a paste with one call:
+Full REST API: [docs/API.md](docs/API.md). One example:
 
 ```bash
-curl -X POST http://localhost:8080/api/pastes \
+curl -X POST http://localhost:8080/api/pastes -d '{"content":"hello"}'
-  -H "Content-Type: application/json" \
-  -d '{"content": "print(hello)", "language": "python", "expires_in": "168h"}'
 ```
 
-Full API docs: [docs/API.md](docs/API.md). Design docs: [docs/design/](docs/design/) (currently: [client-side E2E encryption](docs/design/e2e-encryption.md), issue #39).
+Design docs: [docs/design/](docs/design/).
 
 ## Performance Notes