Emit installed extensions in telemetry for all commands

[Copilot]

Extension telemetry (id, version) is currently only emitted for extension commands (ext.run). For standard commands like azd up or azd deploy, we have no visibility into what extensions the user has installed—relevant when extensions hook into core command lifecycles.

Changes

• internal/tracing/fields/fields.go — New AttributeKey definitions: extensions.installed.ids and extensions.installed.versions (string slices, SystemMetadata/FeatureInsight)
• cmd/middleware/telemetry.go — setInstalledExtensionsAttributes lists installed extensions via the manager and sets sorted ID/version pairs on the command span. Called unconditionally for all commands; no-ops when manager is nil or no extensions are installed.

Example span output for azd up with two extensions installed:

{
  "Name": "cmd.up",
  "Attributes": [
    {
      "Key": "extensions.installed.ids",
      "Value": ["microsoft.azd.ai", "microsoft.azd.demo"]
    },
    {
      "Key": "extensions.installed.versions",
      "Value": ["1.2.0", "0.5.0"]
    }
  ]
}

IDs are sorted lexicographically; versions are positionally aligned.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>tracing - emit installed extensions for non-extension commands</issue_title>
<issue_description>Currently, for custom extension commands we emit something like:

{
"Name": "ext.run",
"Attributes" [
{
    "Key": "cmd.entry",
    "Value": {
        "Type": "STRING",
        "Value": "cmd.demo.ai"
    }
},
{
    "Key": "extension.id",
    "Value": {
        "Type": "STRING",
        "Value": "microsoft.azd.demo"
    }
},
{
    "Key": "extension.version",
    "Value": {
        "Type": "STRING",
        "Value": "0.5.0"
    }
},
]
}

However, for standard azd commands like azd up, azd deploy, etc. we do not currently emit any info on what extensions the user has installed, which can be valuable especially if extensions are invoked as part of core commands via custom service/framework target or lifecycle event hooks.

As a first step we can start by emitting the list of installed extension IDs and versions.</issue_description>

<agent_instructions>cli/azd/docs/tracing-in-azd.md may be helpful, as well as existing patterns</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes tracing - emit installed extensions for non-extension commands #6917

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