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superseded docs under docs/.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/intelligence.json

@@ -0,0 +1,36 @@
+{
+  "hotspots": [
+    {
+      "label": "receive_edited_media()",
+      "risk": 0.62,
+      "type": "FUNCTION"
+    },
+    {
+      "label": "deploy_player_to_host()",
+      "risk": 0.614,
+      "type": "FUNCTION"
+    },
+    {
+      "label": "add_player()",
+      "risk": 0.592,
+      "type": "FUNCTION"
+    },
+    {
+      "label": "upload_media()",
+      "risk": 0.537,
+      "type": "FUNCTION"
+    },
+    {
+      "label": "manage_player()",
+      "risk": 0.429,
+      "type": "FUNCTION"
+    }
+  ],
+  "blast_radius": {
+    "log_action()": 116,
+    "PlayerEdit": 99,
+    "PlayerUser": 74,
+    "Playlist": 33,
+    "CaddyConfigGenerator": 31
+  }
+}