fix(cli): narrow Nous Hermes non-agentic warning to actual hermes-3/-4 models

The startup warning that Nous Research Hermes 3 & 4 models are not agentic
fired on any model whose name contained "hermes" anywhere, via a plain
substring check. That false-positived on unrelated local Modelfiles such
as `hermes-brain:qwen3-14b-ctx16k` — a tool-capable Qwen3 wrapper that
happens to live under a custom "hermes" tag namespace — making the warning
noise for legitimate setups.

Replace the substring check with a narrow regex anchored on `^`, `/`, or
`:` boundaries that only matches the real Hermes-3 / Hermes-4 chat family
(e.g. `NousResearch/Hermes-3-Llama-3.1-70B`, `hermes-4-405b`,
`openrouter/hermes3:70b`). Consolidate into a single helper
`is_nous_hermes_non_agentic()` in `hermes_cli.model_switch` so the CLI
and the canonical check don't drift, and route the duplicate inline site
in `cli.HermesCLI._print_warnings()` through the helper.

Add a parametrized test covering positive matches (real Hermes-3/-4
names) and a broad set of negatives (custom Modelfiles, Qwen/Claude/GPT,
older Nous-Hermes-2 families, bare "hermes", empty string, and the
"brain-hermes-3-impostor" boundary case).

cli.py

@@ -2999,8 +2999,10 @@ class HermesCLI:
                 )
 
         # Warn if the configured model is a Nous Hermes LLM (not agentic)
+        from hermes_cli.model_switch import is_nous_hermes_non_agentic
+
         model_name = getattr(self, "model", "") or ""
-        if "hermes" in model_name.lower():
+        if is_nous_hermes_non_agentic(model_name):
             self.console.print()
             self.console.print(
                 "[bold yellow]⚠  Nous Research Hermes 3 & 4 models are NOT agentic and are not "