agent: Use inventory for AgentPreview (#30740)

This PR updates the `AgentPreview` to use `inventory` instead of
`linkme`.

Release Notes:

- N/A

Cargo.lock

@@ -81,12 +81,12 @@ dependencies = [
  "http_client",
  "indexed_docs",
  "indoc",
+ "inventory",
  "itertools 0.14.0",
  "jsonschema",
  "language",
  "language_model",
  "language_model_selector",
- "linkme",
  "log",
  "lsp",
  "markdown",
@@ -8160,26 +8160,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "linkme"
-version = "0.3.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22d227772b5999ddc0690e733f734f95ca05387e329c4084fe65678c51198ffe"
-dependencies = [
- "linkme-impl",
-]
-
-[[package]]
-name = "linkme-impl"
-version = "0.3.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "71a98813fa0073a317ed6a8055dcd4722a49d9b862af828ee68449adb799b6be"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.100",
-]
-
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.15"
@@ -15682,7 +15662,6 @@ dependencies = [
  "gpui",
  "icons",
  "itertools 0.14.0",
- "linkme",
  "menu",
  "serde",
  "settings",
@@ -15714,7 +15693,6 @@ name = "ui_macros"
 version = "0.1.0"
 dependencies = [
  "convert_case 0.8.0",
- "linkme",
  "proc-macro2",
  "quote",
  "syn 1.0.109",