fix: preserve dots in model names for OpenCode Zen and ZAI providers (#8794)

OpenCode Zen was in _DOT_TO_HYPHEN_PROVIDERS, causing all dotted model
names (minimax-m2.5-free, gpt-5.4, glm-5.1) to be mangled. The fix:

Layer 1 (model_normalize.py): Remove opencode-zen from the blanket
dot-to-hyphen set. Add an explicit block that preserves dots for
non-Claude models while keeping Claude hyphenated (Zen's Claude
endpoint uses anthropic_messages mode which expects hyphens).

Layer 2 (run_agent.py _anthropic_preserve_dots): Add opencode-zen and
zai to the provider allowlist. Broaden URL check from opencode.ai/zen/go
to opencode.ai/zen/ to cover both Go and Zen endpoints. Add bigmodel.cn
for ZAI URL detection.

Also adds glm-5.1 to ZAI model lists in models.py and setup.py.

Closes #7710

Salvaged from contributions by:
- konsisumer (PR #7739, #7719)
- DomGrieco (PR #8708)
- Esashiero (PR #7296)
- sharziki (PR #7497)
- XiaoYingGee (PR #8750)
- APTX4869-maker (PR #8752)
- kagura-agent (PR #7157)

tests/hermes_cli/test_model_normalize.py

@@ -54,14 +54,19 @@ class TestAnthropicDotToHyphen:
 
 # ── OpenCode Zen regression ────────────────────────────────────────────
 
-class TestOpenCodeZenDotToHyphen:
-    """OpenCode Zen follows Anthropic convention (dots→hyphens)."""
+class TestOpenCodeZenModelNormalization:
+    """OpenCode Zen preserves dots for most models, but Claude stays hyphenated."""
 
     @pytest.mark.parametrize("model,expected", [
         ("claude-sonnet-4.6", "claude-sonnet-4-6"),
-        ("glm-4.5", "glm-4-5"),
+        ("opencode-zen/claude-opus-4.5", "claude-opus-4-5"),
+        ("glm-4.5", "glm-4.5"),
+        ("glm-5.1", "glm-5.1"),
+        ("gpt-5.4", "gpt-5.4"),
+        ("minimax-m2.5-free", "minimax-m2.5-free"),
+        ("kimi-k2.5", "kimi-k2.5"),
     ])
-    def test_zen_converts_dots(self, model, expected):
+    def test_zen_normalizes_models(self, model, expected):
         result = normalize_model_for_provider(model, "opencode-zen")
         assert result == expected
 
@@ -69,6 +74,10 @@ class TestOpenCodeZenDotToHyphen:
         result = normalize_model_for_provider("opencode-zen/claude-sonnet-4.6", "opencode-zen")
         assert result == "claude-sonnet-4-6"
 
+    def test_zen_strips_vendor_prefix_for_non_claude(self):
+        result = normalize_model_for_provider("opencode-zen/glm-5.1", "opencode-zen")
+        assert result == "glm-5.1"
+
 
 # ── Copilot dot preservation (regression) ──────────────────────────────