pres_mgmt config: remove legacy launcher option, add back button + dirty state to config UI

- Remove show__launcher_link_legacy from PressMgmtRemoteCfg, PresMgmtLocState, and
  pres_mgmt_loc_defaults — the Flask/legacy launcher is retired
- Sync function now hardcodes hide__launcher_link_legacy=true (always hidden)
- Config page: back button to pres_mgmt, save buttons disabled until changes made
- Fix {#each} key expressions in config page
- Migrate e_app_access_type and element_manage_event_file_li to pres_mgmt_loc store
- Add temporary svelte type augments file (src/types/)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/stores/ae_events_stores__pres_mgmt_defaults.ts

@@ -54,7 +54,6 @@ export interface PressMgmtRemoteCfg {
     show__copy_access_link: boolean;
     show__email_access_link: boolean;
     show__launcher_link: boolean;
-    show__launcher_link_legacy: boolean;
 
     // Requirements
     require__presenter_agree: boolean;
@@ -193,7 +192,6 @@ export interface PresMgmtLocState {
     show__copy_access_link: boolean;
     show__email_access_link: boolean;
     show__launcher_link: boolean;
-    show__launcher_link_legacy: boolean;
     require__presenter_agree: boolean;
     require__session_agree: boolean;
     limit__navigation: boolean;
@@ -367,7 +365,6 @@ export const pres_mgmt_loc_defaults: PresMgmtLocState = {
     show__copy_access_link: false,
     show__email_access_link: false,
     show__launcher_link: false,
-    show__launcher_link_legacy: false,
     require__presenter_agree: false,
     require__session_agree: false,
     limit__navigation: false,