Beta branch integration and PR readiness

[paullizer]

Summary

• Integrates the broad beta branch into Development, including workspace, chat, governance, workflow, agent/action, file sync, data management, documentation, and validation updates.
• Adds final PR-readiness cleanup: whitespace hygiene, Admin Settings JSON rendering XSS cleanup, Semantic Kernel loader BOM removal, and reviewed BAC guardrail justifications for plugin authorization boundaries.
• Bumps the app version to 0.242.065 and adds release/fix documentation for the readiness cleanup.

Validation

• PASS: git diff --check origin/Development
• PASS: Python compile for 539 changed Python files
• PASS: Swagger route validation for 48 changed route files
• PASS: targeted full-file BAC scan for edited plugin/loader files
• PASS: changed Admin Settings appVersion XSS line scan
• PASS: node --check for 74 changed first-party JavaScript files

Tests

• PASS: functional_tests/test_xss_guardrails_checker.py
• PASS: functional_tests/test_broken_access_control_guardrails_checker.py
• PASS: functional_tests/test_broken_access_control_findings_fix.py
• PASS: functional_tests/test_plugin_tool_agent_security_audit.py
• PASS: functional_tests/test_msg_file_upload_support.py
• PASS: functional_tests/test_agents_catalog_feature.py
• PASS: functional_tests/test_governance_enforcement_logic.py
• PASS: functional_tests/test_group_manage_settings_tab_visibility.py
• PASS: functional_tests/test_privacy_logging_telemetry_audit.py
• PASS: functional_tests/test_public_workspace_manage_asset_versioning.py
• PASS: functional_tests/test_azd_managed_identity_preflight.py

Release Notes

• Updated docs/explanation/release_notes.md under v0.242.065.
• Added docs/explanation/fixes/PR_READINESS_GUARDRAIL_CLEANUP_FIX.md and linked it from the fixes index.

Security Notes

• No changed .env, session-token, key/cert/db, node_modules, cache, or storage-state paths were found.
• Route decorators, XSS guardrail spot validation, and targeted BAC validation passed.
• Broad authenticated UI tests were not run locally; validation used syntax checks and focused functional coverage instead.