refactor(sort): introduce build_tmp_sort utility; apply to event_presentation and journals

Creates src/lib/ae_core/core__idb_sort.ts with build_tmp_sort() — a shared
helper for computing tmp_sort_1/2/3 fields stored in Dexie. Fixes two bugs
present in all generic _process_generic_props implementations:
  - priority encoded as 0/1 ASC (true sorted last); now inverted: true→'0'
  - sort stored as unpadded string ("10" < "2"); now 8-char zero-padded

Applied to:
  - ae_events__event_presentation: replaces inline specific_processor code
  - ae_journals__journal + ae_journals__journal_entry: replaces manual formulas;
    journal liveQueries (.reverse().sortBy()) updated to plain .sortBy() since
    the inverted encoding handles direction without needing Dexie's .reverse()

Other modules (sessions, presenters, locations, posts, core) left unchanged
until their sort behavior is reviewed separately.

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

src/routes/journals/+page.svelte

@@ -59,7 +59,6 @@ let lq__journal_obj_li = $derived(
         return await db_journals.journal
             .where('person_id')
             .equals($ae_loc.person_id)
-            .reverse()
             .sortBy('tmp_sort_3');
     })
 );

src/routes/journals/[journal_id]/entry/[journal_entry_id]/+page.svelte

@@ -105,7 +105,6 @@ let lq__journal_obj_li = $derived(
         let results = await db_journals.journal
             .where('person_id')
             .equals($ae_loc.person_id)
-            .reverse()
             .sortBy('tmp_sort_2');
 
         // Check if results are different than the current session version stored under $journals_slct