docs: trim spec frontmatter to known fields (title only)

Official extension specs (ext-auth) use only `title:` in frontmatter
plus an <Info> protocol-revision marker. Remove the invented
extension_identifier / status / maintainers / related / profile_of
fields and restate the identifier and profile relationship in the body
prose where they belong.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

specification/draft/action-metadata.mdx

@@ -1,15 +1,11 @@
 ---
 title: Action Metadata
-extension_identifier: io.modelcontextprotocol/action-metadata
-status: Draft (experimental)
-maintainers:
-  - "@rreichel3"
-  - "@SamMorrowDrums"
-related:
-  - https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2061
-  - https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1913
 ---
 
+<Info>**Protocol Revision**: draft</Info>
+
+**Extension identifier:** `io.modelcontextprotocol/action-metadata`
+
 > ⚠️ **Experimental draft skeleton.** This carries forward
 > [SEP-2061: Action Security Metadata](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2061)
 > by [@rreichel3](https://github.com/rreichel3) into the IG's experimental repo,

specification/draft/ifc-fides.mdx

@@ -1,15 +1,11 @@
 ---
 title: Information-Flow Control (FIDES profile)
-extension_identifier: io.modelcontextprotocol/ifc-fides
-status: Draft (experimental)
-maintainers:
-  - "@SamMorrowDrums"
-profile_of: io.modelcontextprotocol/trust-annotations
-related:
-  - https://arxiv.org/abs/2505.23643
-  - https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1913
 ---
 
+<Info>**Protocol Revision**: draft</Info>
+
+**Extension identifier:** `io.modelcontextprotocol/ifc-fides` &nbsp;·&nbsp; **Profile of:** `io.modelcontextprotocol/trust-annotations`
+
 > ⚠️ **Experimental draft skeleton.** This defines a *profile* of the
 > [`trust-annotations`](./trust-annotations.mdx) `evidenceRef` slot. It is **not**
 > a standalone wire root — see [Why a profile](#why-a-profile).

specification/draft/trust-annotations.mdx

@@ -1,15 +1,11 @@
 ---
 title: Trust Annotations
-extension_identifier: io.modelcontextprotocol/trust-annotations
-status: Draft (experimental)
-maintainers:
-  - "@SamMorrowDrums"
-  - "@rreichel3"
-related:
-  - https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1913
-  - https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/seps/2133-extensions.md
 ---
 
+<Info>**Protocol Revision**: draft</Info>
+
+**Extension identifier:** `io.modelcontextprotocol/trust-annotations`
+
 > ⚠️ **Experimental draft skeleton.** This document captures the agreed shape
 > and the open questions. Normative text is intentionally thin pending
 > reference-implementation validation. Substantive discussion happens on PRs