feat: add MCP healthcheck probes and new templates (grafana, home-assistant, node-red)

- Add healthCheck spec to templates and servers (tool, arguments, interval, timeout, failureThreshold)
- Add healthStatus, lastHealthCheck, events fields to instances
- Create grafana, home-assistant, node-red templates with healthcheck probes
- Add healthcheck probes to existing templates (github, slack, postgres, jira)
- Show HEALTH column in `get instances` and Events section in `describe instance`
- Display healthCheck details in `describe server` and `describe template`
- Schema + storage + display only; actual probe runner is future work

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/db/prisma/schema.prisma

@@ -62,6 +62,7 @@ model McpServer {
   containerPort Int?
   replicas      Int             @default(1)
   env           Json            @default("[]")
+  healthCheck   Json?
   version       Int             @default(1)
   createdAt     DateTime        @default(now())
   updatedAt     DateTime        @updatedAt
@@ -96,6 +97,7 @@ model McpTemplate {
   containerPort Int?
   replicas      Int       @default(1)
   env           Json      @default("[]")
+  healthCheck   Json?
   createdAt     DateTime  @default(now())
   updatedAt     DateTime  @updatedAt
 
@@ -140,10 +142,13 @@ model McpInstance {
   containerId String?
   status      InstanceStatus @default(STOPPED)
   port        Int?
-  metadata    Json           @default("{}")
-  version     Int            @default(1)
-  createdAt   DateTime       @default(now())
-  updatedAt   DateTime       @updatedAt
+  metadata        Json           @default("{}")
+  healthStatus    String?
+  lastHealthCheck DateTime?
+  events          Json           @default("[]")
+  version         Int            @default(1)
+  createdAt       DateTime       @default(now())
+  updatedAt       DateTime       @updatedAt
 
   server McpServer @relation(fields: [serverId], references: [id], onDelete: Cascade)