Register the Elastic Stack logo as a hub product icon (#3875)

* Register the Elastic Stack logo as a hub product icon

Reuse logo_elastic_stack.svg for the elastic-stack hero and link-card key so stack hub pages do not fall back to a letter chip.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Declare the products hub prefix as a navigation phantom

Isolated docs-content builds reject pages under prefixes that assembler navigation does not claim. A real toc entry would fail assembler until the hub pages exist on docs-content main.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Revert "Declare the products hub prefix as a navigation phantom"

This reverts commit 97de7e9.

* Format the elastic-stack icon entry for curb.

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: florent-leborgne

docs/syntax/hero.md

@@ -24,7 +24,7 @@ The `:title:` option doubles as the page title, so a hub page needs no body H1.
 |---|---|---|
 | `:title:` | string | **Required.** Renders as the page `<h1>` next to the icon. Also used as the document title. |
 | `:description:` | inline markdown | One-line summary below the title. Supports bold, italics, and links. |
-| `:icon:` | string | Product key. Resolves to an inline SVG. Known keys: `elasticsearch`, `kibana`, `observability`, `security`. An unknown key falls back to a single-letter chip. |
+| `:icon:` | string | Product key. Resolves to an inline SVG. Known keys: `elasticsearch`, `kibana`, `logstash`, `observability`, `security`, `elastic-stack`. An unknown key falls back to a single-letter chip. |
 | `:primary-action:` | markdown link | First action. Format: `[Label](/url)` or `[Label](#anchor)`. |
 | `:secondary-action:` | markdown link | Second action. |
 | `:tertiary-action:` | markdown link | Third action. |

docs/syntax/link-card.md

@@ -41,7 +41,7 @@ sub-list, so every group of links reads the same way wherever it appears.
 
 `variant: es`, `obs`, or `sec` adds a left border in the matching solution colour. Use it for solution cards.
 
-`icon` takes the same product keys as [`{hero}`](hero.md): `elasticsearch`, `kibana`, `observability`, `security`.
+`icon` takes the same product keys as [`{hero}`](hero.md): `elasticsearch`, `kibana`, `logstash`, `observability`, `security`, `elastic-stack`.
 
 ## Inside `{explore}`
 

src/Elastic.Markdown/Myst/Directives/Hub/ProductIcons.cs

@@ -58,6 +58,14 @@ public static class ProductIcons
 					<path fill="rgba(255,255,255,0.85)" d="M0,20 L0,20 C0,26.627 5.373,32 12,32 L13,32 L13,20 L0,20 Z"/>
 				</g>
 			</svg>
+			""",
+		["elastic-stack"] =
+			"""
+			<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" aria-hidden="true">
+				<path fill="#F04E98" d="M0 2.37A2.37 2.37 0 0 1 2.37 0h27.26A2.37 2.37 0 0 1 32 2.37v6.52H0V2.37Z"/>
+				<path fill="#00BFB3" d="M0 20.148h32v-8.296H0v8.296Z"/>
+				<path fill="#07C" d="M0 23.111h32v6.519A2.37 2.37 0 0 1 29.63 32H2.37A2.37 2.37 0 0 1 0 29.63v-6.52Z"/>
+			</svg>
 			"""
 	}.ToFrozenDictionary(StringComparer.OrdinalIgnoreCase);