feat(ui): the M of the wordmark is the logo

The stylised M replaces the letter M in "MeshBay" at the top left; `eshBay`
beside it stays text.

**The source artwork is now in git.** It was in `QE/`, which is gitignored, so
it would not have survived a clone — and the tree is about to be moved to
another machine. `assets/brand/` holds the original and the `convert` command
that derives the 10 KB nav asset from it (trimmed, 72px tall for a picture shown
at 30, so it survives a 2× screen). Verified: the documented command reproduces
the committed file byte for byte.

The derived file is in `_ASSETS`, which is what the `/a/<hash>/` fingerprint is
computed from. A file missing from that list is a file whose change never moves
the URL, so a browser holding the old one never asks again — the comment on that
list says so, and a logo is exactly the kind of asset one would forget.

Its URL is resolved from `import.meta.url`, so the hub's fingerprinted path and
the application's `app://` scheme both come out right without either being named
in the source.

**The two sizes are independent, and that took four rounds to get right.** The
picture's height was written in `em` — a fraction of the lettering — so every
adjustment to the text resized the picture by the same stroke and the ratio
between them could never change. The operator spotted the coupling before I did
("si on change la taille du M, tu vas encore tout décaler"). The height is in
pixels now: `font-size: 1.375em` (22px) and `height: 30px`, two knobs that move
one thing each. The vertical nudge went with it — it was correcting a
misalignment I was causing myself.

Also: the wordmark blue goes one step down from sky-400 towards sky-500. It sat
brighter than the picture next to it, which made the two read as different
materials rather than one object.

A note on how this went wrong first: I checked the result on a mock HTML page I
wrote, not in the application. The picture was loading the whole time, but at
25px against a 29px line box it was *smaller* than the letters, so the wordmark
read as unchanged and the report was "none of what I asked for was done". Every
size since has been measured in the running window over CDP.

883 tests pass.

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

1 files changed, 8 insertions, 1 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/app.js b/packages/meshbay-hub/src/meshbay_hub/static/app.js
index 0843d1d..2e3c422 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/app.js
@@ -400,6 +400,11 @@ const ICON_PATHS = {
   close:    ['M6 6l12 12M18 6L6 18'],
 };
 
+// The M of the wordmark is a picture; the rest is text. Resolved from this
+// module's own URL so the hub's fingerprinted path and the application's
+// app:// scheme both come out right without either being named here.
+const BRAND_M = new URL('./meshbay-m.png', import.meta.url).href;
+
 function Icon({ name, cls = '' }) {
   const paths = ICON_PATHS[name];
   if (!paths) return null;
@@ -579,7 +584,9 @@ function Nav({ user, theme, onThemeChange, onLogout, onMenuToggle, unreadCount,
           <button class="nav-hamburger" onClick=${onMenuToggle}
             aria-label="${t('nav.toggle_menu')}"><${Icon} name="menu" /></button>
         `}
-        <a class="nav-brand" href="#/">MeshBay</a>
+        <a class="nav-brand" href="#/">
+          <img class="nav-brand-m" src=${BRAND_M} alt="M" />eshBay
+        </a>
       </div>
       <div class="nav-right">
         ${user && html`<${TransferWidget} />`}