Exclude NOTE entries tagged with NOP from project note overview

NOP means „not a project“, so excluding them is plausible per se.  NOP entries
will also be reviewed less frequently (usually once per month) so a combination
of NOTE and NOP would allow to have „abstract“ project notes whose main purpose
is to collect backlinks and thus group proper note entries (example: topics
relevant for release planning).

init.el

@@ -1015,10 +1015,10 @@
               org-agenda-span 1
               org-agenda-insert-diary-strategy 'top-level
               org-catch-invisible-edits 'show
-              org-agenda-sorting-strategy '((agenda time-up habit-up priority-down)
-                                            (todo priority-down category-keep)
-                                            (tags priority-down category-keep)
-                                            (search category-keep))
+              org-agenda-sorting-strategy '((agenda time-up priority-down effort-up category-keep)
+                                            (todo priority-down effort-up category-keep)
+                                            (tags priority-down effort-up category-keep)
+                                            (search priority-down effort-up category-keep))
               org-agenda-window-setup 'current-window
               org-agenda-restore-windows-after-quit t
               org-agenda-compact-blocks nil
@@ -1136,8 +1136,8 @@
                           (org-agenda-todo-ignore-scheduled 'future)))
                   (tags "TODO=\"\"-TAGS={NOP\\|TOPIC}-PERIODIC-NOTE-DATE-SOMEWHEN-HOLD-TEMPLATE-SCHEDULED>=\"<+1d>\""
                         ((org-agenda-overriding-header "Open Tasks")))
-                  (tags "TAGS={NOTE}-TODO={CANC\\|DONE}-HOLD"
-                        ((org-agenda-overriding-header "Project Notes (items explicitly tagged with NOTE)")))
+                  (tags "TAGS={NOTE}-TODO={CANC\\|DONE}-HOLD-NOP"
+                        ((org-agenda-overriding-header "Project Notes (items explicitly tagged with NOTE but not NOP)")))
                   (tags "TODO=\"\"+TAGS={TOPIC}-SCHEDULED>=\"<+1d>\""
                         ((org-agenda-overriding-header "Topics")))
                   (tags "TAGS={PERIODIC}-TODO={DONE\\|CANC}-HOLD-SCHEDULED>=\"<+1d>\""