Add node tag import functionality to collector

- Add tag_import.py module with JSON file parsing and database upsert
- Convert collector CLI to group with subcommands for extensibility
- Add 'import-tags' command to import tags from JSON file
- Update docker-compose.yml.example with separated data directories:
  - data/collector for tags.json
  - data/web for members.json
- Add import-tags Docker service for easy containerized imports
- Add example data files in example/data/collector and example/data/web
- Add comprehensive test coverage (20 tests) for tag import

example/data/collector/tags.json

@@ -0,0 +1,28 @@
+{
+  "tags": [
+    {
+      "public_key": "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+      "key": "location",
+      "value": "San Francisco, CA",
+      "value_type": "string"
+    },
+    {
+      "public_key": "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+      "key": "role",
+      "value": "gateway",
+      "value_type": "string"
+    },
+    {
+      "public_key": "fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210",
+      "key": "location",
+      "value": "Oakland, CA",
+      "value_type": "string"
+    },
+    {
+      "public_key": "fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210",
+      "key": "altitude",
+      "value": "150",
+      "value_type": "number"
+    }
+  ]
+}

example/data/web/members.json

@@ -0,0 +1,10 @@
+{
+  "members": [
+    {
+      "name": "Example Member",
+      "callsign": "N0CALL",
+      "role": "Network Operator",
+      "description": "Example member entry"
+    }
+  ]
+}