fix: Ollama Cloud auth, /model switch persistence, and alias tab completion

- Add OLLAMA_API_KEY to credential resolution chain for ollama.com endpoints
- Update requested_provider/_explicit_api_key/_explicit_base_url after /model
  switch so _ensure_runtime_credentials() doesn't revert the switch
- Pass base_url/api_key from fallback config to resolve_provider_client()
- Add DirectAlias system: user-configurable model_aliases in config.yaml
  checked before catalog resolution, with reverse lookup by model ID
- Add /model tab completion showing aliases with provider metadata

Co-authored-by: LucidPaths <LucidPaths@users.noreply.github.com>

hermes_cli/commands.py

@@ -745,6 +745,39 @@ class SlashCommandCompleter(Completer):
             )
             count += 1
 
+    def _model_completions(self, sub_text: str, sub_lower: str):
+        """Yield completions for /model from config aliases + built-in aliases."""
+        seen = set()
+        # Config-based direct aliases (preferred — include provider info)
+        try:
+            from hermes_cli.model_switch import (
+                _ensure_direct_aliases, DIRECT_ALIASES, MODEL_ALIASES,
+            )
+            _ensure_direct_aliases()
+            for name, da in DIRECT_ALIASES.items():
+                if name.startswith(sub_lower) and name != sub_lower:
+                    seen.add(name)
+                    yield Completion(
+                        name,
+                        start_position=-len(sub_text),
+                        display=name,
+                        display_meta=f"{da.model} ({da.provider})",
+                    )
+            # Built-in catalog aliases not already covered
+            for name in sorted(MODEL_ALIASES.keys()):
+                if name in seen:
+                    continue
+                if name.startswith(sub_lower) and name != sub_lower:
+                    identity = MODEL_ALIASES[name]
+                    yield Completion(
+                        name,
+                        start_position=-len(sub_text),
+                        display=name,
+                        display_meta=f"{identity.vendor}/{identity.family}",
+                    )
+        except Exception:
+            pass
+
     def get_completions(self, document, complete_event):
         text = document.text_before_cursor
         if not text.startswith("/"):
@@ -766,6 +799,11 @@ class SlashCommandCompleter(Completer):
             sub_text = parts[1] if len(parts) > 1 else ""
             sub_lower = sub_text.lower()
 
+            # Dynamic model alias completions for /model
+            if " " not in sub_text and base_cmd == "/model":
+                yield from self._model_completions(sub_text, sub_lower)
+                return
+
             # Static subcommand completions
             if " " not in sub_text and base_cmd in SUBCOMMANDS:
                 for sub in SUBCOMMANDS[base_cmd]: