Add scan flow MVP and local Axiom skill workspace

This snapshot establishes the camera-to-result recognition flow and related tests while checking in the project skill/docs assets required for the configured local tooling.

StackDex/Services/VisionCardOCRService.swift

@@ -0,0 +1,83 @@
+import CoreGraphics
+import Vision
+
+struct RecognizedTextLine: Equatable {
+    let text: String
+    let confidence: Double
+    let normalizedBounds: CGRect
+}
+
+struct OCRTextPayload: Equatable {
+    let rawText: String
+    let lines: [RecognizedTextLine]
+    let averageConfidence: Double
+}
+
+protocol CardTextRecognizing {
+    func recognizeText(in image: PreparedImage) async throws -> OCRTextPayload
+}
+
+enum VisionCardOCRServiceError: LocalizedError {
+    case noRecognizedText
+
+    var errorDescription: String? {
+        switch self {
+        case .noRecognizedText:
+            return "Vision OCR could not find readable card text."
+        }
+    }
+}
+
+struct VisionCardOCRService: CardTextRecognizing {
+    private let customWords = [
+        "Pokémon", "Charizard", "Glurak", "Pikachu", "Blastoise", "Venusaur",
+        "Illustration", "Scarlet", "Violet", "Trainer", "Holo", "Rare", "Ultra",
+        "VMAX", "GX", "ex", "Base", "Set", "Promo", "Shiny"
+    ]
+
+    func recognizeText(in image: PreparedImage) async throws -> OCRTextPayload {
+        try await withCheckedThrowingContinuation { continuation in
+            let request = VNRecognizeTextRequest { request, error in
+                if let error {
+                    continuation.resume(throwing: error)
+                    return
+                }
+
+                let observations = (request.results as? [VNRecognizedTextObservation]) ?? []
+                let lines = observations.compactMap { observation -> RecognizedTextLine? in
+                    guard let candidate = observation.topCandidates(1).first else { return nil }
+                    return RecognizedTextLine(
+                        text: candidate.string,
+                        confidence: Double(candidate.confidence),
+                        normalizedBounds: observation.boundingBox
+                    )
+                }
+
+                guard !lines.isEmpty else {
+                    continuation.resume(throwing: VisionCardOCRServiceError.noRecognizedText)
+                    return
+                }
+
+                let average = lines.map(\.confidence).reduce(0, +) / Double(lines.count)
+                continuation.resume(returning: OCRTextPayload(
+                    rawText: lines.map(\.text).joined(separator: "\n"),
+                    lines: lines,
+                    averageConfidence: average
+                ))
+            }
+
+            request.recognitionLevel = .accurate
+            request.recognitionLanguages = ["en-US", "de-DE"]
+            request.usesLanguageCorrection = true
+            request.customWords = customWords
+
+            let handler = VNImageRequestHandler(cgImage: image.analysisCGImage, options: [:])
+
+            do {
+                try handler.perform([request])
+            } catch {
+                continuation.resume(throwing: error)
+            }
+        }
+    }
+}