Add comprehensive task list and VSCode todo-tree integration

Add docs/TASKS.md:
- Completed tasks (6): K3S, Flux, ESS, Themes, Desktop Scripts, Monitoring, TURN
- In Progress: Authentik Stage 2 (pending manual config)
- Backlog (15+): Element Call Fork, PostgreSQL migration, NetworkPolicies, etc.
- Security hardening: Host/Cluster/App layer recommendations
- Milestones: Track progress from M1 (Basic) to M7 (Enterprise)

Enhance devcontainer.json:
- Add gruntfuggly.todo-tree extension for task tree view
- Add ms-vscode.makefile-tools for build automation
- Add GitHub.copilot for development assistance
- Configure todo-tree to highlight TASKS.md and deployment guides

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.devcontainer/devcontainer.json

@@ -26,7 +26,10 @@
         "redhat.vscode-yaml",
         "redhat.vscode-commons",
         "monokai.theme-monokai-pro-vscode",
-        "eamodio.gitlens"
+        "eamodio.gitlens",
+        "gruntfuggly.todo-tree",
+        "ms-vscode.makefile-tools",
+        "GitHub.copilot"
       ],
       "settings": {
         "[yaml]": {
@@ -38,7 +41,22 @@
           "https://json.schemastore.org/kustomization.json": "**/kustomization.yaml",
           "https://json.schemastore.org/helmrelease.json": "**/*helmrelease*.yaml"
         },
-        "editor.theme": "Monokai Pro"
+        "editor.theme": "Monokai Pro",
+        "todo-tree.general.showActivityBarBadge": true,
+        "todo-tree.general.tags": [
+          "TODO",
+          "FIXME",
+          "BUG",
+          "HACK",
+          "NOTE",
+          "XXX",
+          "DONE"
+        ],
+        "todo-tree.tree.showScanModeButton": true,
+        "todo-tree.filtering.includeGlobs": [
+          "**/docs/TASKS.md",
+          "**/docs/deployment-guides/*.md"
+        ]
       }
     }
   },