Switch Gmail and Gcal to env-var OAuth delivery pattern

auth.deliver changes from as:file to as:env:
- Gmail: GMAIL_CREDS_JSON env var (Google authorized_user JSON)
- Gcal: GCAL_CREDS_JSON env var

mcp_config.env removed entirely — Skald injects the env var at runtime,
no path on disk needed.

Server scripts updated:
- Check GMAIL_CREDS_JSON / GCAL_CREDS_JSON env var first
- Use Credentials.from_authorized_user_info() instead of
  from_authorized_user_file()
- Fall back to file-based loading for standalone/legacy use
- _persist_creds only writes to disk when _creds_path is set

gcal/verify.py: support GCAL_CREDS_JSON env var with shared _check_api()

Docs (SKALD.md): updated examples, field table, connector table.

connectors/gcal/verify.py

@@ -1,9 +1,12 @@
 #!/usr/bin/env python3
 """Verify Google Calendar OAuth credentials are valid.
 
-Reads GOOGLE_CREDS_PATH env var (or falls back to secrets/google_creds.json),
-loads the authorized_user credentials, and does one cheap API probe
-(calendarList.list(maxResults=1)).
+Priority:
+1. GCAL_CREDS_JSON env var — authorized_user JSON injected by Skald.
+2. GOOGLE_CREDS_PATH env var → file on disk (standalone).
+3. Default path ./secrets/google_creds.json (standalone).
+
+Loads credentials and does one cheap API probe (calendarList.list(maxResults=1)).
 
 Output: single JSON object on stdout:
   {"ok": true, "message": "..."}
@@ -17,40 +20,20 @@ import os
 import sys
 
 
-def main() -> None:
-    creds_path = os.environ.get(
-        "GOOGLE_CREDS_PATH",
-        os.path.join(os.path.dirname(__file__), "secrets", "google_creds.json"),
-    )
-
-    if not os.path.exists(creds_path):
-        _fail(f"Credentials file not found at {creds_path}. Run gcal_oauth_setup.py first.")
-        return
-
+def _check_api(creds) -> None:
+    """Perform a live Calendar API probe with the given credentials."""
     try:
         from google.auth.transport.requests import Request
-        from google.oauth2.credentials import Credentials
         from googleapiclient.discovery import build
     except ImportError as e:
         _fail(f"Missing dependencies: {e}. Install google-api-python-client and google-auth.")
         return
 
-    try:
-        creds = Credentials.from_authorized_user_file(
-            creds_path,
-            ["https://www.googleapis.com/auth/calendar"],
-        )
-    except Exception as e:
-        _fail(f"Failed to load credentials: {e}")
-        return
-
     if creds.expired and creds.refresh_token:
         try:
             creds.refresh(Request())
-            with open(creds_path, "w") as f:
-                f.write(creds.to_json())
         except Exception as e:
-            _fail(f"Token refresh failed: {e}. Re-run gcal_oauth_setup.py.")
+            _fail(f"Token refresh failed: {e}")
             return
 
     try:
@@ -64,12 +47,60 @@ def main() -> None:
         _fail(f"API probe failed: {e}")
 
 
+def main() -> None:
+    # Priority 1: env var with full JSON (Skald mode)
+    raw = os.environ.get("GCAL_CREDS_JSON")
+    if raw:
+        try:
+            from google.oauth2.credentials import Credentials
+            creds = Credentials.from_authorized_user_info(
+                json.loads(raw),
+                ["https://www.googleapis.com/auth/calendar"],
+            )
+            _check_api(creds)
+            return
+        except ImportError as e:
+            _fail(f"Missing dependencies: {e}. Install google-api-python-client and google-auth.")
+            return
+        except Exception as e:
+            _fail(f"Failed to load credentials from GCAL_CREDS_JSON: {e}")
+            return
+
+    # Priority 2/3: file-based (standalone use)
+    creds_path = os.environ.get(
+        "GOOGLE_CREDS_PATH",
+        os.path.join(os.path.dirname(__file__), "secrets", "google_creds.json"),
+    )
+
+    if not os.path.exists(creds_path):
+        _fail(f"Credentials not found. Set GCAL_CREDS_JSON env var (Skald mode) or "
+              f"place credentials file at {creds_path} (standalone mode).")
+        return
+
+    try:
+        from google.oauth2.credentials import Credentials
+        creds = Credentials.from_authorized_user_file(
+            creds_path,
+            ["https://www.googleapis.com/auth/calendar"],
+        )
+    except ImportError as e:
+        _fail(f"Missing dependencies: {e}. Install google-api-python-client and google-auth.")
+        return
+    except Exception as e:
+        _fail(f"Failed to load credentials: {e}")
+        return
+
+    _check_api(creds)
+
+
 def _ok(message: str) -> None:
     json.dump({"ok": True, "message": message}, sys.stdout)
+    sys.stdout.write("\n")
 
 
 def _fail(message: str) -> None:
     json.dump({"ok": False, "message": message}, sys.stdout)
+    sys.stdout.write("\n")
     sys.exit(1)