Brand: inbuxa's own kitten replaces ihasmail's cat

inbuxa's mark was ihasmail's cat-and-envelope reused unchanged. The new
one keeps the family's face, paws and colors, over a server with a bay
for each piece of the suite: the letter (webmail), a prompt (console),
status lights (server).

- The built-in sign-in and calendar RSVP pages, and the web logo, drew
  the old cat as an embedded PNG. They now draw the mark as vector in
  the same slot, keeping class="symbol"; each page is about 31 KB
  lighter. The .min copies are updated the same way and the .min.gz
  regenerated with gzip -9 -n, as minify_html.sh does.
- resources/branding: email-logo.png (the compact lockup at 380x80 on
  white, as before) with its .b64 regenerated byte-for-byte in the old
  76-column form, and favicon-64.png.
- img/brand: the logo bundle, now pure vector, with its README.

img/brand/README.txt

@@ -1,11 +1,18 @@
 inbuxa logo bundle
 ===================
 
-Mark: reused from ihasmail's actual cat-and-envelope artwork (ihasmail-mark.png),
-unmodified. Colors sampled directly from that file:
+Mark (since 2026-09-27): inbuxa's own kitten -- the ihasmail cat peeking over
+a server box with three bays, one for each piece of the suite: the letter
+(webmail), a >_ prompt (console) and status lights (server). The face, paws
+and whiskers are the family's, so it reads beside ihasmail's envelope cat and
+ihasvpn's shield cat without being mistaken for either. Pure vector: no
+embedded bitmap anywhere in the SVGs.
   navy outline   #1C4053
   cat orange     #F9A34C  (inner ear #F47F35)
-  envelope teal  #46CAC3
+  server teal    #46CAC3  (bays #1C4053, lower band #2B8A86, lights #9FF0E9)
+
+The previous set, with ihasmail's cat-and-envelope reused unchanged, is kept
+in previous-ihasmail-cat/.
 
 Wordmark set in Space Grotesk (Bold for "inbuxa", Medium for the "MAIL SERVER"
 tag line), rendered as true vector paths in the SVGs -- no font install needed
@@ -13,7 +20,7 @@ to view or edit them correctly in any vector app.
 
 Files
 -----
-inbuxa-icon.svg / .png              Mark only, square, for favicons/app icons
+inbuxa-icon.svg / .png              Mark only, square, transparent, for favicons/app icons
 inbuxa-lockup-light.svg / .png      Full hero lockup, white background
 inbuxa-lockup-dark.svg / .png       Full hero lockup, dark background
 inbuxa-lockup-compact-light.svg/.png  Compact lockup (icon + "inbuxa" only),
@@ -26,3 +33,8 @@ inbuxa-lockup-190x40-dark.png       Same, dark background
 Dark backgrounds use #0B1720 rather than pure black -- a shade darker than the
 mark's own navy outline, so the outline still reads as a lighter edge instead
 of disappearing into the page.
+
+The name
+--------
+"inbuxa" is "inbox" the way Tiny Tina would say it. Hearing her say
+"Gearbox" in the Borderlands games inspired the name.