Add versioned Latest Features navigation hide preference

[Bionic711]

Summary

• Adds a version-aware Latest Features navigation hide preference backed by latestFeaturesHiddenVersion user UI settings.
• Hides Latest Features nav entries only for the current config.py version, with automatic reappearance after a version bump.
• Adds Profile Settings controls to restore the Latest Features navigation entries.
• Adds a development-only is_development=true override for local validation.
• Adds feature documentation and release notes for version 0.250.059.

Fixes #987

Validation

Passed:

• git diff --check origin/Development...HEAD
• git diff --check
• Python compile check for application/single_app and changed tests
• python scripts/check_swagger_routes.py for changed Python route/application files
• Route policy inventory, unauthenticated policy contract, and route policy coverage tests
• XSS changed-line sink scan
• Broken access-control changed-line scan
• node --check application/single_app/static/js/latest-features-nav.js
• functional_tests/test_latest_features_action_links.py
• functional_tests/test_latest_features_nav_hide_preference.py

Skipped:

• ui_tests/test_latest_features_nav_hide_preference.py ran under pytest but skipped because local SIMPLECHAT_UI_BASE_URL and authenticated Playwright storage state were not configured.

Documentation And Release Notes

• Added docs/explanation/features/LATEST_FEATURES_NAVIGATION_HIDE_PREFERENCE.md.
• Updated docs/explanation/release_notes.md under v0.250.059.

Security Notes

• No changed paths matched .env, secret, token, session, connection-string, storage-key, or generated local artifact patterns.
• Route decorator/policy, XSS, and broken-access-control checks passed.