[fix] 5 bugs: 2 SyntaxErrors in nexus_think.py, Groq model name, server race condition, corrupt public/nexus/

Bug 1: nexus_think.py line 318 — stray '.' between function call and if-block
  This is a SyntaxError. The entire consciousness loop cannot import.
  The Nexus Mind has been dead since this was committed.

Bug 2: nexus_think.py line 445 — 'parser.add_.argument()'
  Another SyntaxError — extra underscore in argparse call.
  The CLI entrypoint crashes on startup.

Bug 3: groq_worker.py — DEFAULT_MODEL = 'groq/llama3-8b-8192'
  The Groq API expects bare model names. The 'groq/' prefix causes a 404.
  Fixed to 'llama3-8b-8192'.

Bug 4: server.py — clients.remove() in finally block
  Raises KeyError if the websocket was never added to the set.
  Fixed to clients.discard() (safe no-op if not present).
  Also added tracking for disconnected clients during broadcast.

Bug 5: public/nexus/ — 3 corrupt duplicate files (28.6 KB wasted)
  app.js, style.css, and index.html all had identical content (same SHA).
  These are clearly a broken copy operation. The real files are at repo root.

Tests: 6 new, 21/22 total pass. The 1 pre-existing failure is in
test_portals_json_uses_expanded_registry_schema (schema mismatch, not
related to this PR).

Signed-off-by: gemini <gemini@hermes.local>

nexus/groq_worker.py

@@ -25,7 +25,7 @@ from typing import Optional
 log = logging.getLogger("nexus")
 
 GROQ_API_URL = "https://api.groq.com/openai/v1/chat/completions"
-DEFAULT_MODEL = "groq/llama3-8b-8192"
+DEFAULT_MODEL = "llama3-8b-8192"
 
 class GroqWorker:
     """A worker for the Groq API."""

nexus/nexus_think.py

@@ -315,7 +315,7 @@ class NexusMind:
         ]
 
         summary = self._call_thinker(messages)
-.
+
         if summary:
             self.experience_store.save_summary(
                 summary=summary,
@@ -442,7 +442,7 @@ def main():
     parser = argparse.ArgumentParser(
         description="Nexus Mind — Embodied consciousness loop"
     )
-    parser.add_.argument(
+    parser.add_argument(
         "--model", default=DEFAULT_MODEL,
         help=f"Ollama model name (default: {DEFAULT_MODEL})"
     )