feat(honeybar): the HoneyOS bar, loaded at runtime

A strip along the top that leads to the other apps of the same system. It is
served by HoneyOS; InkNote only says where to find it, through
INKNOTE_HONEYBAR_ORIGIN. Empty means no bar and no change at all.

The origin is served by the API rather than built into the page, because an
image is pulled ready-made and a service worker keeps whole responses: anything
frozen into index.html would outlive the setting.

Layout follows the bar through --honeybar-h. The body has overflow:hidden, so
the surplus height would not have scrolled but been cut off at the bottom; and
#root padded itself around the notch that the bar now covers, which would have
counted that gap twice.

Unit 263/263, all fourteen browser suites green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docker-compose.yml

@@ -30,6 +30,11 @@ services:
       # Optional tuning; unset means the server's own defaults apply.
       - ALLOWED_ORIGINS=${ALLOWED_ORIGINS:-}
       - INKNOTE_MAX_IMAGE_MB=${INKNOTE_MAX_IMAGE_MB:-}
+      # HoneyOS bar. Empty origin means no bar at all; the key is only needed
+      # when HoneyOS sits on a different site, where the browser withholds its
+      # session. Takes effect on restart — nothing here is baked into the image.
+      - INKNOTE_HONEYBAR_ORIGIN=${INKNOTE_HONEYBAR_ORIGIN:-}
+      - INKNOTE_HONEYBAR_KEY=${INKNOTE_HONEYBAR_KEY:-}
       - INKNOTE_MAX_PDF_MB=${INKNOTE_MAX_PDF_MB:-}
       - MAX_VERSIONS_PER_NOTE=${MAX_VERSIONS_PER_NOTE:-}
       - VERSION_RETENTION_DAYS=${VERSION_RETENTION_DAYS:-}