fix(dogfood): update display name and add README (#24487)

Update the `vscode-coder` dogfood template with better naming,
documentation, and agent testing instructions.

dogfood/main.tf

@@ -100,7 +100,7 @@ resource "coderd_template" "dogfood" {
 
 resource "coderd_template" "vscode_coder" {
   name            = "vscode-coder"
-  display_name    = "Write VS Code Extension on Coder"
+  display_name    = "Write Coder VS Code Extension on Coder"
   description     = "Develop the coder/vscode-coder VS Code extension on Coder."
   icon            = "/icon/code.svg"
   organization_id = data.coderd_organization.default.id

dogfood/vscode-coder/README.md

@@ -0,0 +1,35 @@
+# vscode-coder template
+
+This template is for developing the
+[coder/vscode-coder](https://github.com/coder/vscode-coder) VS Code extension.
+
+## Personalization
+
+The template includes a `personalize` module that runs your `~/personalize`
+file if it exists.
+
+## Testing
+
+The workspace comes with Playwright Chromium, GTK libraries, xauth, and a
+D-Bus daemon pre-configured for running tests headlessly, the same way CI
+does.
+
+Integration tests launch a real VS Code instance and require a virtual
+framebuffer. Run them with `xvfb-run -a pnpm test:integration` to match
+CI behavior.
+
+See the repo's
+[AGENTS.md](https://github.com/coder/vscode-coder/blob/main/AGENTS.md)
+for the full list of commands.
+
+## Hosting
+
+Coder dogfoods on a single Teraswitch bare metal machine for best-in-class
+cost-to-performance. Workspaces run as Docker containers with regional
+Tailscale endpoints for Pittsburgh, Falkenstein, Sydney, and Cape Town.
+
+## Provisioner Configuration
+
+The dogfood coderd box runs an SSH tunnel to the Docker host's socket,
+mounted at `/var/run/dogfood-docker.sock`. The tunnel runs in a screen
+session named `forward` and is owned by root.

dogfood/vscode-coder/main.tf

@@ -364,6 +364,18 @@ resource "coder_agent" "dev" {
     timeout      = 60
   }
 
+  metadata {
+    display_name = "Word of the Day"
+    key          = "word"
+    order        = 3
+    script       = <<EOT
+      #!/usr/bin/env bash
+      curl -o - --silent https://www.merriam-webster.com/word-of-the-day 2>&1 | awk ' $0 ~ "Word of the Day: [A-z]+" { print $5; exit }'
+    EOT
+    interval     = 86400
+    timeout      = 5
+  }
+
   resources_monitoring {
     memory {
       enabled   = true
@@ -551,6 +563,13 @@ locals {
     - Built-in tools for everything:
       (file operations, git commands, builds & installs, one-off shell commands)
 
+    -- Testing --
+    Integration tests launch a real VS Code instance and require a
+    virtual framebuffer. Run them headlessly with:
+      xvfb-run -a pnpm test:integration
+    This matches how CI runs them. Unit tests do not need xvfb-run:
+      pnpm test
+
     -- Workflow --
     When starting new work:
     1. If given a GitHub issue URL, use the `gh` CLI to read the full