Add upload/download ratio and period transfer panels to Transmission dashboard (#6)

## Summary
- Adds Upload/Download Ratio stat panel with color thresholds (red < 0.5, yellow < 1, green >= 1)
- Adds Downloaded (Period) stat panel showing bytes downloaded in selected time range
- Adds Uploaded (Period) stat panel showing bytes uploaded in selected time range

Uses PromQL `increase()` on existing counter metrics - no new metrics collection needed.

## Test plan
- [x] Deployed to indri via `mise run provision-indri`
- [x] Grafana restarted successfully

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/6

ansible/roles/grafana/files/dashboards/transmission.json

@@ -285,6 +285,149 @@
       "title": "Total Uploaded",
       "type": "stat"
     },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "decimals": 2,
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {"color": "red", "value": null},
+              {"color": "yellow", "value": 0.5},
+              {"color": "green", "value": 1}
+            ]
+          },
+          "unit": "none"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 8, "x": 0, "y": 4},
+      "id": 11,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {"type": "prometheus", "uid": "prometheus"},
+          "expr": "increase(transmission_uploaded_bytes_total[$__range]) / increase(transmission_downloaded_bytes_total[$__range])",
+          "refId": "A"
+        }
+      ],
+      "title": "Upload/Download Ratio (Period)",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "fixedColor": "green",
+            "mode": "fixed"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {"color": "green", "value": null}
+            ]
+          },
+          "unit": "decbytes"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 8, "x": 8, "y": 4},
+      "id": 12,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {"type": "prometheus", "uid": "prometheus"},
+          "expr": "increase(transmission_downloaded_bytes_total[$__range])",
+          "refId": "A"
+        }
+      ],
+      "title": "Downloaded (Period)",
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "fixedColor": "blue",
+            "mode": "fixed"
+          },
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {"color": "blue", "value": null}
+            ]
+          },
+          "unit": "decbytes"
+        },
+        "overrides": []
+      },
+      "gridPos": {"h": 4, "w": 8, "x": 16, "y": 4},
+      "id": 13,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "none",
+        "justifyMode": "auto",
+        "orientation": "auto",
+        "reduceOptions": {
+          "calcs": ["lastNotNull"],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "auto"
+      },
+      "pluginVersion": "10.0.0",
+      "targets": [
+        {
+          "datasource": {"type": "prometheus", "uid": "prometheus"},
+          "expr": "increase(transmission_uploaded_bytes_total[$__range])",
+          "refId": "A"
+        }
+      ],
+      "title": "Uploaded (Period)",
+      "type": "stat"
+    },
     {
       "datasource": {
         "type": "prometheus",
@@ -351,7 +494,7 @@
           }
         ]
       },
-      "gridPos": {"h": 8, "w": 12, "x": 0, "y": 4},
+      "gridPos": {"h": 8, "w": 12, "x": 0, "y": 8},
       "id": 7,
       "options": {
         "legend": {
@@ -436,7 +579,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 8, "w": 12, "x": 12, "y": 4},
+      "gridPos": {"h": 8, "w": 12, "x": 12, "y": 8},
       "id": 8,
       "options": {
         "legend": {
@@ -540,7 +683,7 @@
           }
         ]
       },
-      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 12},
+      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 16},
       "id": 9,
       "options": {
         "legend": {
@@ -626,7 +769,7 @@
         },
         "overrides": []
       },
-      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 20},
+      "gridPos": {"h": 8, "w": 24, "x": 0, "y": 24},
       "id": 10,
       "options": {
         "legend": {