feat(mavweb): /ecosystem page consuming Nexus/Praxis/Hexis + shell fixes

Add a read-only /ecosystem page that consumes the sibling services'
JSON APIs (Nexus entities, Praxis attention, Hexis capabilities),
fetched concurrently with honest per-panel error states. Siblings stay
headless — mavweb is their human surface (arch §16). Wired via mavweb
-nexus/-praxis/-hexis flags; mavweb joins the ecosystem compose network.

Fix mobile horizontal overflow across all pages: .content is a flex
child with default min-width:auto, so it refused to shrink below the
tables' intrinsic width. min-width:0 lets wide tables pan inside .scroll
instead of dragging the page sideways. Verified via CDP geometry check
(scrollWidth === clientWidth at 430px).

Also includes in-progress Ethos UI redesign, ecosystem deploy compose,
and planning docs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/mavend.json

@@ -18,6 +18,10 @@
     "chat_id": "${TELEGRAM_CHAT_ID}"
   },
 
+  "nexus":  { "url": "http://nexus:9740" },
+  "praxis": { "url": "http://praxis:8989" },
+  "hexis":  { "url": "http://hexis:9741" },
+
   "voice": {
     "enabled": true,
     "bind": "0.0.0.0:9100",