fix(auth): honor SSL CA env vars across httpx + requests callsites

- hermes_cli/auth.py: add _default_verify() with macOS Homebrew certifi
  fallback (mirrors weixin 3a0ec1d93). Extend env var chain to include
  REQUESTS_CA_BUNDLE so one env var works across httpx + requests paths.
- agent/model_metadata.py: add _resolve_requests_verify() reading
  HERMES_CA_BUNDLE / REQUESTS_CA_BUNDLE / SSL_CERT_FILE in priority
  order. Apply explicit verify= to all 6 requests.get callsites.
- Tests: 18 new unit tests + autouse platform pin on existing
  TestResolveVerifyFallback to keep its "returns True" assertions
  platform-independent.

Empirically verified against self-signed HTTPS server: requests honors
REQUESTS_CA_BUNDLE only; httpx honors SSL_CERT_FILE only. Hermes now
honors all three everywhere.

Triggered by Discord reports — Nous OAuth SSL failure on macOS
Homebrew Python; custom provider self-signed cert ignored despite
REQUESTS_CA_BUNDLE set in env.

agent/model_metadata.py

@@ -6,6 +6,7 @@ and run_agent.py for pre-flight context checks.
 
 import ipaddress
 import logging
+import os
 import re
 import time
 from pathlib import Path
@@ -21,6 +22,25 @@ from hermes_constants import OPENROUTER_MODELS_URL
 
 logger = logging.getLogger(__name__)
 
+
+def _resolve_requests_verify() -> bool | str:
+    """Resolve SSL verify setting for `requests` calls from env vars.
+
+    The `requests` library only honours REQUESTS_CA_BUNDLE / CURL_CA_BUNDLE
+    by default. Hermes also honours HERMES_CA_BUNDLE (its own convention)
+    and SSL_CERT_FILE (used by the stdlib `ssl` module and by httpx), so
+    that a single env var can cover both `requests` and `httpx` callsites
+    inside the same process.
+
+    Returns either a filesystem path to a CA bundle, or True to defer to
+    the requests default (certifi).
+    """
+    for env_var in ("HERMES_CA_BUNDLE", "REQUESTS_CA_BUNDLE", "SSL_CERT_FILE"):
+        val = os.getenv(env_var)
+        if val and os.path.isfile(val):
+            return val
+    return True
+
 # Provider names that can appear as a "provider:" prefix before a model ID.
 # Only these are stripped — Ollama-style "model:tag" colons (e.g. "qwen3.5:27b")
 # are preserved so the full model name reaches cache lookups and server queries.
@@ -495,7 +515,7 @@ def fetch_model_metadata(force_refresh: bool = False) -> Dict[str, Dict[str, Any
         return _model_metadata_cache
 
     try:
-        response = requests.get(OPENROUTER_MODELS_URL, timeout=10)
+        response = requests.get(OPENROUTER_MODELS_URL, timeout=10, verify=_resolve_requests_verify())
         response.raise_for_status()
         data = response.json()
 
@@ -562,6 +582,7 @@ def fetch_endpoint_model_metadata(
                     server_url.rstrip("/") + "/api/v1/models",
                     headers=headers,
                     timeout=10,
+                    verify=_resolve_requests_verify(),
                 )
                 response.raise_for_status()
                 payload = response.json()
@@ -610,7 +631,7 @@ def fetch_endpoint_model_metadata(
     for candidate in candidates:
         url = candidate.rstrip("/") + "/models"
         try:
-            response = requests.get(url, headers=headers, timeout=10)
+            response = requests.get(url, headers=headers, timeout=10, verify=_resolve_requests_verify())
             response.raise_for_status()
             payload = response.json()
             cache: Dict[str, Dict[str, Any]] = {}
@@ -641,9 +662,10 @@ def fetch_endpoint_model_metadata(
                 try:
                     # Try /v1/props first (current llama.cpp); fall back to /props for older builds
                     base = candidate.rstrip("/").replace("/v1", "")
-                    props_resp = requests.get(base + "/v1/props", headers=headers, timeout=5)
+                    _verify = _resolve_requests_verify()
+                    props_resp = requests.get(base + "/v1/props", headers=headers, timeout=5, verify=_verify)
                     if not props_resp.ok:
-                        props_resp = requests.get(base + "/props", headers=headers, timeout=5)
+                        props_resp = requests.get(base + "/props", headers=headers, timeout=5, verify=_verify)
                     if props_resp.ok:
                         props = props_resp.json()
                         gen_settings = props.get("default_generation_settings", {})
@@ -992,7 +1014,7 @@ def _query_anthropic_context_length(model: str, base_url: str, api_key: str) ->
             "x-api-key": api_key,
             "anthropic-version": "2023-06-01",
         }
-        resp = requests.get(url, headers=headers, timeout=10)
+        resp = requests.get(url, headers=headers, timeout=10, verify=_resolve_requests_verify())
         if resp.status_code != 200:
             return None
         data = resp.json()