ESM-native resource manager

Managed resources are ES modules loaded via import() and resolved through the page's import map; the manager keeps a name→specifier registry for load-once and version switching, instead of SPF's classic-script system (manual require/unrequire/declare dependency graphs and script.path). Native module semantics replace the dependency manager, and version bumps become import-map changes on the server. Classic <script> tags inside fragment HTML remain supported as unmanaged resources (executed in order, navigation waits unless async) because real pages ship third-party classic scripts.

• Status: accepted
• Considered Options: (a) full SPF manager — dependency graphs are obsolete with native modules; (b) slim classic-script manager — would maintain two script systems; (c) ESM-native — chosen.
• Consequences: an ES module cannot be truly unmounted once loaded; "unload" means dropping the registry entry so the next load re-resolves the specifier (possibly to a new version via an updated import map).