rename: opencortex → passepartout across memex

- .gitmodules: update submodule paths (projects/opencortex → projects/passepartout,
  projects/opencortex-contrib → projects/passepartout-contrib)
- gtd.org, README.org: update project references and display names
- check.lisp, gemini-vision.org, agora/TODO.org: update file paths
- dotemacs: update agenda paths and template config
- system/plans/: update all flight plan references
- system/backups/: update monolithic backup references

projects/dotemacs/templates/ATOMIC_NOTES_SETUP.org

@@ -17,7 +17,7 @@ MEMEX_DAILY="memex/1_daily"
 MEMEX_NOTES="memex/2_notes"
 MEMEX_DRAFTS="memex/3_drafts"
 MEMEX_PUBLISHED="memex/4_published"
-MEMEX_PROJECTS="memex/5_projects"
+MEMEX_PROJECTS="memex/projects"
 MEMEX_AREAS="memex/6_areas"
 MEMEX_RESOURCES="memex/7_resources"
 MEMEX_ARCHIVES="memex/8_archives"