Rewrite the README and add a recorded demo

Rework the README into the house style: badges, a one-line pitch, an
anchor nav, a commands table, and dedicated sections for clone, pack, and
the native viewer. Every flag and default is checked against the current
binary so the docs match what kage actually does.

Add a demo recorded with ascii-gif. The tape clones example.com, packs it
to a ZIM and to a self-contained binary, and serves it back offline, so
the whole loop reads in one frame. It sits at the top of the README and on
the docs home.

While reviewing the docs, fix the output path everywhere: the default is
$HOME/data/kage, not the kage-out the pages claimed, including a few
fabricated 'done kage-out/...' lines. Document pack, open, and the native
viewer in the release notes.

docs/content/reference/configuration.md

@@ -24,7 +24,7 @@ A clone of `example.com` lands under `$HOME/data/kage/example.com/` (override th
 root with `-o/--out`):
 
 ```
-kage-out/example.com/
+$HOME/data/kage/example.com/
 ├── index.html                  # the home page (/), scripts stripped
 ├── about/index.html            # /about
 ├── blog/

docs/content/reference/release-notes.md

@@ -9,6 +9,25 @@ The authoritative, commit-level history lives in
 [releases page](https://github.com/tamnd/kage/releases). This page summarises
 each version.
 
+## Unreleased
+
+Packing, so a clone can travel as one file instead of a folder.
+
+- **`kage pack <mirror-dir>`** collapses a mirror into a single distributable
+  file. `--format zim` (the default) writes an open ZIM archive, the same format
+  Kiwix uses; `--format binary` appends that archive to a copy of kage to make a
+  self-contained executable that serves the site offline when run. Packing is
+  deterministic, so the same mirror produces a byte-identical file.
+- **`kage open <file.zim>`** serves a packed ZIM back over a local HTTP server,
+  the read side of `kage pack --format zim`.
+- **An optional native-window viewer.** Built with `-tags webview`, `kage open`
+  and a packed binary show the site in a real window backed by the operating
+  system's WebView instead of a browser tab. The default build stays pure Go and
+  opens the browser, so the release pipeline is unchanged.
+- **A pure-Go `zim` package** that reads and writes the ZIM format: a fixed
+  header, MIME and pointer lists, zstd or stored clusters, redirects, and a
+  trailing MD5.
+
 ## v0.1.0
 
 The first release. kage clones a live website into a self-contained folder you