Improve content loading, TOML utilities, runtime setup, theme caching, and login throttle pruning

[remdui]

Motivation

• Harden and simplify content loading and example scaffolding by centralizing TOML load/render helpers and adding strict validation support.
• Prevent file-system traversal and stale/generated-file issues by validating entity IDs and pruning old login throttle records.
• Ensure the runtime environment directories exist on startup and improve theme discovery caching by including static file signatures.

Description

• Introduced mylonite.core.toml_utils with render_toml and load_toml_file and migrated TOML I/O to use these helpers across the codebase.
• Added strict content-validation support to PortfolioContentLoader (strict_validation flag) plus ContentValidationError, changed validation to apply schema defaults for missing values, and surfaced validation errors via loader tracking.
• Tightened content repository and scaffold behaviors by adding is_valid_entity_id checks and rejecting invalid/path-traversal object IDs, and switched scaffold code to use render_toml.
• Added prune_stale_login_throttles and invoke it in throttle inspection and registration, and introduced PANEL_LOGIN_THROTTLE_RETENTION_SECONDS setting.
• Introduced runtime path utilities (resolve_runtime_paths, RuntimePaths, ensure_runtime_directories) and ensure runtime dirs are created in manage.py and wsgi.py, and updated settings.py to use those paths and the new TOML loader.
• Improved theme discovery signature in ThemeResolver to include per-file static signatures to avoid stale cache entries.
• Updated view models, mapping and templates to expose an intro_markdown field and prefer owner.bio for hero bio when available.

Testing

• Ran unit tests covering modified modules including tests/apps/panel/test_services.py, tests/apps/web/test_content.py, tests/apps/web/test_content_scaffold.py, tests/apps/web/test_architecture_extensions.py, tests/apps/web/test_view_models.py, and tests/mylonite/core/test_core_modules.py via pytest and all tests passed.

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Codex Task