Svelte client fixes

[yrodzikau]

Svelte client: LayerView feature parity, System Settings values, dialog overflow and UI event fixes

This PR brings the Svelte client closer to the Vue 2 client and fixes several
server-side issues in the V2 frontend (/api/frontend) that the Svelte client
depends on. It is rebased on the current develop (after "Added Layerview
transforms"); the LayerView changes were merged with the new coordinate
transform / axes indicator code.

Server (Implementation/UI)

• Page show events in the V2 frontend. CUIPage::frontendWritePageStatusToJSON()
  now writes showevent, so AMCPage.setActive() triggers it again. Without it
  the ScanlabOCM System Settings page showed the config.xml defaults instead of
  the active machine configuration.
• Values set by UI event handlers are reported. CUIFrontendState::writeModuleAttributesToJSON()
  writes the session client variable for an attribute when one exists
  (set via UIEnvironment::SetUIProperty), instead of the definition value.
  Attributes bound with sync: are still evaluated from the state machine, as
  in the legacy syncClientVariables(). Adds
  CUIFrontendDefinitionAttribute::isSynchronized(),
  writeClientValueToFrontendJSON() and CUIFrontendDefinitionModuleStore::getPath().
• LayerView base image resolved to a UUID in client variables. Client
  variables take precedence over module attributes in the new frontend, so the
  resource name written by populateClientVariables() overrode the resolved
  UUID and the Svelte client could not load the platform image. The name is now
  resolved through one shared helper in all three places; an empty name yields
  the null UUID (empty string for the dark image = fall back to the light one).
• Unit tests: new UIFrontend test group (amc_unittests_uifrontend.hpp).

Client core (shared JS)

• triggerUIEvent(): an errorcode in the /event response or a failed
  request is shown in the snackbar via the new showEventError(); the success
  path no longer runs for a failed event.
• New showSnackBar() sets every snackbar field and bumps a Sequence
  counter, so repeated identical messages restart the auto-hide timer.
• triggerWidgetRequest(): optional failureCallback(err) for callers that
  need to roll back optimistic UI state.
• Removed the mouse-move debug logging from WebGLLocalizedPointsElement.

Svelte client

• LayerView at the Vue 2 feature set: scatter plot points and the laser
  channel (laseron, power), color modes, LaserOff point toggle, toolpath
  visibility toggle, hover info for the point / toolpath segment under the
  cursor (one raycast per animation frame), platform label and loading
  indicator. Layer slider: correct range (layercount - 1), changelayer sent
  only on release, -/+ step buttons, sliderfixed support, optimistic change
  with rollback on failure. The canvas and resize observer are re-attached when
  the module is hidden and shown again. Stale toolpath / scatter plot responses
  are ignored; the null UUID is treated as "no build" / "no image".
• BuildList / ExecutionList use the shared triggerButtonEvent() helper:
  selectionvalueuuid receives the item, buttonvalueuuid the button, so the
  server-side handler can tell which button was pressed.
• ConfigurationList: Load / Set Active no longer send a placeholder id as
  the button UUID (rejected by the server with "invalid uuid string"). The
  Delete fallback was removed, no plugin handles deleteconfiguration.
• Tabs: invisible tabs are hidden.
• Dialogs: DialogContent / DialogFooter / DialogTitle (shadcn-svelte)
  get an overflow-safe layout, so long 3MF file names and multiple buttons stay
  inside the dialog (Build Library and Build History details, config.xml
  dialogs). Note: re-running shadcn-svelte add dialog would overwrite these
  files.
• mdi-timer-outline is mapped to the Clock icon.
• Snackbar.svelte reacts to the new Sequence counter.

Vue 2 client

• App.vue: snackBarVisible gets a setter, otherwise Vuetify cannot reset
  Visible and the next error is never shown.

Testing

• amc_unittest passes with the new UIFrontend group.
• svelte-check reports no errors in the touched modules.
• Clean Windows build (build_clean_win64.bat) and a rebuilt Svelte client
  package; the ScanlabOCM configuration was run in simulation mode and a build
  job started and executed layers without errors.

Notes

• Artifacts/clientdist/clientpackage_svelte.zip is not part of these commits
  and must be rebuilt with Artifacts/build_client_svelte_clean.bat.
• <buttongroup> rows in config.xml dialogs still do not wrap.