Sanitize codebase, reorganize docs, and add missing deploy files

Remove dead code identified in docs/SANITIZATION-REVIEW.md:
- app/blueprints/content_old.py and app/blueprints/playlist.py
- app/models/group.py, app/utils/nginx_config_reader.py
- orphaned templates (content_list, edit_content, upload_content,
  player_page) and the related group/Template references

Result: 6 blueprints, 82 routes, no dead modules or orphan templates.

Add files that deploy.sh and docker-entrypoint.sh already require but
which were never tracked:
- https_manager.py       (referenced by deploy.sh, migrate_network.sh,
                          docker-entrypoint.sh)
- Caddyfile.example      (seeded by deploy.sh; its absence aborts deploy)

Relocate generated Graphify artifacts from graphify-out/ to
docs/graphify-out/ (110 files, no content change) and archive the
superseded docs under docs/.

Ignore hygiene:
- ignore ad-hoc .env backups (.env.bak*) — they contain live secrets
- keep the pre-sanitization snapshots (docs/legacy code/,
  docs/old_code_documentation/) on disk but out of the repo

Fix .env.example: drop a duplicated config block, genericize the
hardcoded host IP, and document HOSTNAME_INTERNAL.

docs/graphify-out/DOMAINS.md

@@ -0,0 +1,45 @@
+# System Domains (Communities)
+
+| ID | Domain | Rationale |
+|---|---|---|
+| 0 | Community 0 |  |
+| 1 | Community 1 |  |
+| 2 | Community 2 |  |
+| 3 | Community 3 |  |
+| 4 | Community 4 |  |
+| 5 | Community 5 |  |
+| 6 | Community 6 |  |
+| 7 | Community 7 |  |
+| 8 | Community 8 |  |
+| 9 | Community 9 |  |
+| 10 | Community 10 |  |
+| 11 | Community 11 |  |
+| 12 | Community 12 |  |
+| 13 | Community 13 |  |
+| 14 | Community 14 |  |
+| 15 | Community 15 |  |
+| 16 | Community 16 |  |
+| 17 | Community 17 |  |
+| 18 | Community 18 |  |
+| 19 | Community 19 |  |
+| 20 | Community 20 |  |
+| 21 | Community 21 |  |
+| 22 | Community 22 |  |
+| 23 | Community 23 |  |
+| 24 | Community 24 |  |
+| 25 | Community 25 |  |
+| 26 | Community 26 |  |
+| 27 | Community 27 |  |
+| 28 | Community 28 |  |
+| 29 | Community 29 |  |
+| 30 | Community 30 |  |
+| 31 | Community 31 |  |
+| 32 | Community 32 |  |
+| 33 | Community 33 |  |
+| 34 | Community 34 |  |
+| 35 | Community 35 |  |
+| 36 | Community 36 |  |
+| 37 | Community 37 |  |
+| 38 | Community 38 |  |
+| 39 | Community 39 |  |
+| 40 | Community 40 |  |