Remove disabled-theme/menu workaround once adapt_framework#3802 ships

[taylortom]

Commit 18068c7 ("Fix: Exclude disabled themes/menus from build sources") added a local workaround for adaptlearning/adapt_framework#3802 (PR #3803). With more than one theme installed, the framework's grunt `less:dev` task globs all themes' LESS into a single `adapt.css` and OOMs. The workaround filters disabled `theme` / `menu` plugins out of the build sources in two places.

Once the upstream PR merges and lands in a framework release, the workaround becomes unnecessary and should be removed.

To do once upstream fix is released

• Bump the minimum framework version constraint so a release containing adapt_framework#3803 is required
• Revert `AdaptFrameworkBuild.build` `pluginsToInclude` to `[...enabledPlugins, ...disabledPlugins]`
• Revert `prebuildSharedCache` to calling `copyFrameworkSource` without an `enabledPlugins` filter (and drop the related `includedPlugins` filter / `pluginNames` derivation)

Both spots reference `adapt_framework#3802` in code comments — `grep '#3802' lib/` will surface them.

The prebuilt cache layout already supports per-(theme, menu) CSS keys (`cssDir: ${pluginHash}${theme}${menu}`), so nothing in the cache code itself needs to change.