feat: enrich Settings → App Info with metadata & resource links (#56)

Replaces the three-row App Info screen with a full About/Resources/Support/
Legal layout, driven by a declarative AppInfoRow model with all URLs centralized
in one AppLinks namespace.

- About: Version now shows "5.0.0 (build N)" (CFBundleShortVersionString +
  CFBundleVersion), plus Storage, Backup Schema, and Minimum iOS (17.6).
- Resources: What's New (bundled ReleaseNotes.json sheet, no network),
  Documentation & FAQ, Source Code, Privacy Policy, and Acknowledgements
  ("no third-party dependencies" + MIT license).
- Support: Report an Issue (a sheet that shows the locally-assembled
  version/OS/device diagnostics before offering Email or GitHub — nothing is
  collected silently) and Contact (mailto).
- Support the App: Rate (SwiftUI's @Environment(\.requestReview), which handles
  the scene internally and respects Apple's throttling — the modern, safer
  equivalent of the issue's SKStoreReviewController + connectedScenes path) and
  Share (ShareLink to the App Store listing).
- Legal: copyright footer with the current year.

External rows use Link/openURL with an "opens outside the app" accessibility
hint; the screen is standard adaptive Form controls with semantic colors, so it
tracks Dynamic Type and light/dark automatically.

New files (AppLinks, AppInfo, ReleaseNotes[.swift/.json], AppInfoView) auto-
compile/bundle via the synchronized DomainDig/ group. AppInfoTests covers the
mailto builder, version format, diagnostics contents, and that the bundled notes
ship and parse. Unit suite green.

Placeholder pending the App Store listing: AppLinks.appStoreID (the review/share
URLs derive from it), flagged with a TODO.

1 files changed, 45 insertions, 0 deletions

diff --git a/DomainDigTests/AppInfoTests.swift b/DomainDigTests/AppInfoTests.swift
new file mode 100644
index 0000000..5b574f7
--- /dev/null
+++ b/DomainDigTests/AppInfoTests.swift
@@ -0,0 +1,45 @@
+import XCTest
+@testable import DomainDig
+
+/// Tests for the App Info surface's deterministic logic: the mailto builder, the
+/// version display format, and that the bundled release notes ship and parse.
+final class AppInfoTests: XCTestCase {
+
+    func testMailURLEncodesSubjectAndBody() throws {
+        let url = try XCTUnwrap(AppInfoView.mailURL(
+            to: "[email protected]",
+            subject: "DomainDig Issue Report",
+            body: "line one\nline two"
+        ))
+
+        XCTAssertEqual(url.scheme, "mailto")
+        let string = url.absoluteString
+        XCTAssertTrue(string.hasPrefix("mailto:[email protected]?"))
+        XCTAssertTrue(string.contains("subject=DomainDig%20Issue%20Report"))
+        XCTAssertTrue(string.contains("body=line%20one%0Aline%20two"))
+    }
+
+    func testMailURLOmitsEmptyQueryItems() throws {
+        let url = try XCTUnwrap(AppInfoView.mailURL(to: "[email protected]", subject: "", body: ""))
+        XCTAssertEqual(url.absoluteString, "mailto:[email protected]")
+    }
+
+    func testVersionDisplayPairsMarketingVersionAndBuild() {
+        XCTAssertEqual(AppInfo.versionDisplay, "\(AppInfo.marketingVersion) (build \(AppInfo.buildNumber))")
+    }
+
+    func testDiagnosticsReportContainsVersionOSAndModelOnly() {
+        let report = AppInfo.diagnosticsReport
+        XCTAssertTrue(report.contains(AppInfo.marketingVersion))
+        XCTAssertTrue(report.contains(AppInfo.systemVersion))
+        XCTAssertTrue(report.contains(AppInfo.deviceModel))
+        // Three lines, nothing more — no identifiers beyond version/OS/model.
+        XCTAssertEqual(report.split(separator: "\n").count, 3)
+    }
+
+    func testBundledReleaseNotesShipAndParse() throws {
+        let notes = try XCTUnwrap(ReleaseNotes.bundled(), "ReleaseNotes.json must be bundled and decodable")
+        XCTAssertFalse(notes.version.isEmpty)
+        XCTAssertFalse(notes.highlights.isEmpty)
+    }
+}