Harden startup shell runtime defaults

[cbusillo]

Summary

• normalize /opt/launchplane/addons into startup-generated Odoo config so shell phases can load launchplane_runtime_health
• skip admin hardening when the configured admin login is absent in a restored tenant database
• document the startup/runtime behavior and add regression tests

Tests

• uv run python -m unittest tests.test_odoo_startup
• uv run ruff check --diff README.md docker/scripts/run_odoo_startup.py tests/test_odoo_startup.py
• uv run ruff check README.md docker/scripts/run_odoo_startup.py tests/test_odoo_startup.py
• uv run ruff format --check docker/scripts/run_odoo_startup.py tests/test_odoo_startup.py
• uv run python -m unittest discover -s tests
• git diff --check

Note: README.md was excluded from ruff format because this repo's Ruff reports Markdown formatting as experimental unless preview mode is enabled.