feat: Implement Event File Hosted Data Fix and API Guide Update

Address critical data visibility issues for Event Files and enhance frontend documentation.

This commit resolves the persistent problem where top-level hosted file convenience fields
(e.g., , , ) were
returning as  in V3 Event File API responses, even when .

Key changes include:
- Refactored  Pydantic model:
    - Removed redundant  definitions from top-level hosted file convenience fields,
      allowing direct mapping from SQL view columns.
    - Simplified  to focus solely on conditionally loading the nested
       object, as top-level fields are now populated directly by Pydantic
      from the  view.
    - Added comprehensive comments to clarify data flow, Pydantic's behavior, and the
      expected origin of these convenience fields from SQL views.
- Updated :
    - Introduced a new section detailing how to retrieve Event File data, including the
      use of  to get both top-level convenience fields and a nested
       object.
    - Clarified all ID references as random string IDs.
    - Renumbered the troubleshooting section.
- Copied updated guide to .
- Continued ID Vision compliance audit, ensuring consistent handling of random string IDs
  across various core and event models (Account, Address, Contact, DataStore, Event Badge Template).
- Consolidated ID Vision E2E tests and updated related documentation.
- Minor updates to  and
  to support Event File data retrieval with .

tests/e2e/test_e2e_v3_demo_parity.py

@@ -10,6 +10,7 @@ API_KEY = "PMM4n50teUCaOMMTN8qOJA" # Agent API Key
 # Note: These IDs are extracted from real active records.
 TARGETS = [
     ("event_badge", "JPUG-87-80-88"),
+    ("event_badge_template", "gDcA4kVb5B0"),
     ("event_exhibit", "xK_9yEj1bQY"),
     ("event_exhibit_tracking", "KVypw_xntSY"),
     ("event_file", "a2pPIT_W28o") # Regression Target for Relational ID bug