Show extended profile details on the profile screens (#10)

* Add HealthChat API and extended profile services

Expose OpenID tokens and homeserver credentials from the client proxy, and
add fork-only services for the HealthChat member directory backend
(api.healthchat.ch) plus a service that reads MSC4133 extended profile
fields directly from the homeserver. Groundwork for the members tab and
the profile screens.

Claude-Session: https://claude.ai/code/session_013qdTbAWsZj2quQzEkagXaS

* Show extended profile details on the profile screens

Add a UserProfileScreenHook that lets the fork inject an extra Form
section below the header of the user profile and room member details
screens. The HealthChat implementation loads the MSC4133 extended
profile fields and renders them with tappable phone/email/website
links, hiding the section entirely for profiles without any fields.

Strings live in a new fork-only HealthChat.strings table (de/en/fr,
generated as HealthChatL10n via SwiftGen) since Untranslated.strings
pins the English bundle.

Claude-Session: https://claude.ai/code/session_013qdTbAWsZj2quQzEkagXaS

PreviewTests/Sources/GeneratedPreviewTests.swift

@@ -340,6 +340,13 @@ extension PreviewTests {
         }
     }
 
+    @Test
+    func healthChatExtendedProfileSection() async throws {
+        for (index, preview) in HealthChatExtendedProfileSection_Previews._allPreviews.enumerated() {
+            try await assertSnapshots(matching: preview, step: index)
+        }
+    }
+
     @Test
     func highlightedTimelineItemModifier() async throws {
         for (index, preview) in HighlightedTimelineItemModifier_Previews._allPreviews.enumerated() {

PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Contact-only-iPad-en-GB.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Contact-only-iPad-pseudo.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Contact-only-iPhone-en-GB.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Contact-only-iPhone-pseudo.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Full-profile-iPad-en-GB.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Full-profile-iPad-pseudo.png

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PreviewTests/Sources/__Snapshots__/PreviewTests/healthChatExtendedProfileSection.Full-profile-iPhone-pseudo.png

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