fix(nested-crud): re-inject parent FK after model serialization to prevent 1364 errors

Root cause: child model root_validators (Vision ID anti-leakage guard) strip
integer IDs before they can be serialized into the INSERT dict, causing MariaDB
to reject the INSERT with 'Field does not have a default value' (1364).

Fix: re-inject resolved_parent_id into data_to_insert after validated_obj.dict()
in post_child_obj(). This is safe — the integer was already verified against the
DB before model validation.

Affected (were all broken since ~2026-01-27):
  - journal/{id}/journal_entry/
  - event/{id}/event_session/
  - event/{id}/event_person/
  - event/{id}/event_registration/
  - event/{id}/event_presenter/
  - event/{id}/event_presentation/
  - event/{id}/event_location/
  - event/{id}/event_track/
  - event/{id}/event_device/
  - event/{id}/event_abstract/
  - event/{id}/event_badge/ (different symptom: NULL FK)

Tests: add nested create lifecycle regression tests to test_e2e_v3_demo_parity.py
  - POST + Vision check + DELETE for journal/journal_entry and event/event_session
  - All 9 checks passing (7s)

Docs: update tests/README.md with accurate demo_parity description and
  a 'When to Run Tests' matrix to prevent future gaps in coverage.

tests/README.md

@@ -25,7 +25,7 @@ These consolidated scripts are the primary verification tool for the V3 API.
 | `test_e2e_v3_event_vision_parity.py`| **Vision ID**: Verifies string-ID enforcement across event models. |
 | `test_e2e_v3_cms_vision_parity.py`| **Vision ID**: Verifies string-ID enforcement across CMS (post/comment) models. |
 | `test_e2e_v3_core_vision_parity.py`| **Vision ID**: Verifies string-ID and polymorphic resolution across core models (Account, Person, Address, Contact, DataStore). |
-| `test_e2e_v3_demo_parity.py` | **Demo Parity**: Comprehensive check for Badge, Exhibit, Tracking, and nested Journal Entries. |
+| `test_e2e_v3_demo_parity.py` | **Demo Parity + Nested Create Regression**: Vision ID check for Badge, Exhibit, Tracking; nested create lifecycle (POST+DELETE) for `journal/journal_entry` and `event/event_session`; alias resolution. **Run after any model or nested-router change.** |
 | `test_e2e_v3_action_event_file.py` | **Event Actions**: Specialized atomic upload and linking for event files. |
 | `test_e2e_v3_action_zoom.py` | **Zoom Integration**: Verifies OAuth and ticket sync logic for Zoom Events. |
 | `test_e2e_v3_accounts.py` | CRUD verification for the core Account object. |
@@ -41,6 +41,21 @@ These consolidated scripts are the primary verification tool for the V3 API.
 
 ---
 
+## 🚦 When to Run Tests
+
+Tests exist to be used — run the relevant suite whenever you touch backend code, not just when something breaks.
+
+| Change type | Required suites |
+| :--- | :--- |
+| Model `root_validator` / ID Vision changes | `test_e2e_v3_demo_parity.py`, `test_e2e_v3_event_vision_parity.py`, `test_e2e_v3_core_vision_parity.py` |
+| Nested router (`api_crud_v3_nested.py`) changes | `test_e2e_v3_demo_parity.py` |
+| Search / filter changes | `test_e2e_v3_search_engine.py` |
+| Auth / account context changes | `test_e2e_v3_security_audit.py`, `test_e2e_v3_auth_security.py` |
+| File upload / download changes | `test_e2e_v3_actions_file_lifecycle.py` |
+| Any backend change before frontend hand-off | All of the above |
+
+---
+
 ## 🧹 Maintenance Policy
 
 1.  **Standardization**: All E2E tests should use the standard Agent API Key (`PMM4n50teUCaOMMTN8qOJA`) and provide clean `[✅ PASS]` or `[❌ FAIL]` output.
@@ -67,4 +82,56 @@ To maintain a "nice" and readable test suite, follow these patterns in all new P
 ```
 
 ### Path Requirements
-Always run test scripts from the **project root** directory. Most scripts include `sys.path.append(os.getcwd())` to ensure local imports work correctly.
+Always run test scripts from the **project root** directory. Most scripts include `sys.path.append(os.getcwd())` to ensure local imports work correctly.
+
+
+---
+
+## Development / Testing / Demo environment information
+* Use snake_case (or Snake_Case or Snake_case or test_NASA_example or test_API_key)
+* Aether test/demo base URL: 'http://demo.localhost:5173'
+* Aether development API: 'https://dev-api.oneskyit.com'
+
+These are IDs for records that we can use for testing. Please do not delete them. They are also used for demo purposes with clients.
+
+### Core Modules
+* Aether test/demo Account: '_XY7DXtc9MY' (1) "One Sky IT Demo"
+* Aether test/demo Site: '92vkYC4fVEl' (12) "One Sky IT Demo"
+* Aether test/demo Site Domain: '_6jcTbnJk-o' (12) "demo.localhost:5173"
+* Aether test/demo Site Domain: 'heXRgHOs4ns' (30) "sk-demo.oneskyit.com"
+* Aether test/demo Site Domain: 'DASm8fP92yw' (69) "dev-demo.oneskyit.com"
+* Aether test/demo Site Domain: '2i_0Za6yRPo' (2) "demo.oneskyit.com"
+* Aether test/demo Person: 'QWODAPCNLQU' (49) "Osiris Idem"
+* Aether test/demo Person: 'HMQRNPIXQMK' (48) "Cleo Idem"
+
+### Events Modules
+* Aether test/demo Event: 'pjrcghqwert' (1) "Demo One Sky IT Conference"
+* Aether test/demo Event Session: 'DOW3h7v6H42' (703) "How To Do Things"
+* Aether test/demo Event Session (Digital Posters): "K8cxUIEWyQk" "The Beginning of Digital Posters!"
+* Aether test/demo Event Session (Digital Posters): "1Un1xI1Rgk8" "Poster Session 99: All about posters!"
+* Aether test/demo Event Presentation: '7U2eXSjR6H4' (1670) "Build a House"
+* Aether test/demo Event Presenter: 'gT-hxnifb-0' (2202) "Bob The Builder"
+* Aether test/demo Event File: 'OOsHXtng5mr' (2985) "1 Quick Test for macOS.mp4"
+* Aether test/demo Event Badge: 'UIJT-73-63-61' (37163) "Scott Idem"
+* Aether test/demo Event Person: 'ffkKxiHpOEC' (16603) "Scott Idem"
+* Aether test/demo Event Badge Template: 'jgfixEpYp1B' (18) "Dev Demo 202x"
+* Aether test/demo Event Badge Template: 'rzmUgsk7mkq' (19) "Dev Demo 202x Workshops"
+* Aether test/demo Event Location: 'VXXY-98-46-14' (26) "Ballroom 1"
+* Aether test/demo Event Location: 'FGRN-67-92-45' (298) "Ballroom AB"
+* Aether test/demo Event Location: 'PQKB-15-39-81' (78) "Poster Display Station A"
+
+### Journals Module
+* Aether test/demo Journal: 'BVYE-94-46-29' (42) "Testing Things"
+* Aether test/demo Journal Entry: 'xRx-Y4-h3-fU' (233) "Another Journal Entry in the Test Journal"
+
+### Archives Module (IDAA Archives)
+* Aether test/demo Archive: 'nAA2bHLv8RK' (1) "One Sky Test Archive"
+* Aether test/demo Archive Content: 'UjKzrk-GKu5' (1) "Hosted File Test"
+
+### Posts Module (IDAA Bulletin Board)
+* Aether test/demo Post:
+* Aether test/demo Post:
+
+### Events Module (IDAA Recovery Meetings)
+* Aether test/demo Event: '1Pkd025vvxU' (36) "IDAA Recovery Meeting Test"
+* Aether test/demo Event: 'gIZgAjISkf8' (43) "IDAA Recovery Meeting Test"