feat: add the logo, and point people at the plugin before they mint a token

Logo: the app had no icon at all — public/ held only .gitkeep and the page
emitted no <link rel="icon">, so browsers requested /favicon.ico, got a 404
and showed a blank tab. app/icon.svg is picked up automatically by the App
Router; public/logo.svg is a currentColor variant for in-app use.

The mark is three retrieval signals converging on a single memory, which is
what the search actually does (vector + full-text + tags fused by RRF) and
what the product does (many sessions, one store). Checked at 16px: the outer
strokes are held at equal opacity because asymmetry read as a rendering
artifact rather than as ranking.

Tokens page: reframed so a bearer token is the exception rather than the
default. A token is a credential to store and rotate; the plugin just signs
you in. The install hint renders only when PLUGIN_MARKETPLACE_URL is set —
a copyable command pointing nowhere is worse than no command.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.env.example

@@ -40,6 +40,12 @@ OIDC_CLIENT_ID_WEB=replace-me
 OIDC_CLIENT_SECRET_WEB=replace-me
 OIDC_CLIENT_ID_MCP=replace-me
 OIDC_AUDIENCE=shared-memory
+
+# Marketplace this instance's Claude Code plugin is published from. When set,
+# the CLI tokens page shows the one-command plugin install so people only mint
+# a bearer token when a browser sign-in genuinely isn't possible.
+#PLUGIN_MARKETPLACE_URL=https://your-git-host/you/shared-memory.git
+#PLUGIN_MARKETPLACE_NAME=shared-memory
 # Scope whose IdP mapping emits `aud: <OIDC_AUDIENCE>`. Advertised in
 # /.well-known/oauth-protected-resource so MCP clients request it — without
 # that, Authentik never evaluates the mapping and every token 401s with