Make tracker pattern displayName read-only

The displayName field was always predictable from pattern + matchType
and allowing edits added unnecessary complexity. Remove displayName
from UpdateTrackerPatternInput across all surfaces (GraphQL, MCP, CLI,
n8n) and make the frontend show it as non-editable text.

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/server/api/mcp/v1/specification.yaml

@@ -10012,11 +10012,6 @@ components:
       properties:
         id:
           $ref: "#/components/schemas/GID"
-        display_name:
-          type:
-            - string
-            - "null"
-          go.probo.inc/mcpgen/omittable: true
         max_age_seconds:
           type:
             - integer