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>

.env.example

@@ -24,6 +24,15 @@ INKNOTE_ADMIN_PASSWORD=
 
 # ── Optional ── unset keeps the default shown
 # INKNOTE_MAX_IMAGE_MB=25           # pasted images
+
+# ── HoneyOS bar ───────────────────────────────────────────────────────────────
+# The strip along the top that ties the apps together. Empty = no bar.
+# Wirkt beim Neustart, nicht beim Bauen.
+# INKNOTE_HONEYBAR_ORIGIN=https://honeyos.example.com
+# Only needed when HoneyOS lives on a different site than InkNote — then the
+# browser will not send its session and the bar needs this to fetch the app
+# list. Same domain (notes.example.org + example.org): leave empty.
+# INKNOTE_HONEYBAR_KEY=
 # INKNOTE_MAX_PDF_MB=200            # imported PDFs, limited separately
 # INKNOTE_UID=1000                  # must own INKNOTE_DATA_DIR
 # INKNOTE_GID=1000