Initial implementation of SwiftDBAI

Chat with any SQLite database using natural language. Built on
AnyLanguageModel (HuggingFace) for LLM-agnostic provider support
and GRDB for SQLite access.

Core features:
- Auto schema introspection from sqlite_master (zero config)
- NL → SQL generation via any AnyLanguageModel provider
- Three rendering modes: text summary, data table, Swift Charts
- Drop-in DataChatView (SwiftUI) and headless ChatEngine
- Operation allowlist with read-only default
- Mutation policy with per-table control
- ToolExecutionDelegate for destructive operation confirmation
- Multi-turn conversation context
- 352 tests across 24 suites, all passing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Package.swift

@@ -0,0 +1,41 @@
+// swift-tools-version: 6.1
+
+import PackageDescription
+
+let package = Package(
+    name: "SwiftDBAI",
+    platforms: [
+        .iOS(.v17),
+        .macOS(.v14),
+        .visionOS(.v1),
+    ],
+    products: [
+        .library(
+            name: "SwiftDBAI",
+            targets: ["SwiftDBAI"]
+        ),
+    ],
+    dependencies: [
+        .package(url: "https://github.com/groue/GRDB.swift.git", from: "7.0.0"),
+        .package(url: "https://github.com/huggingface/AnyLanguageModel.git", branch: "main"),
+    ],
+    targets: [
+        .target(
+            name: "SwiftDBAI",
+            dependencies: [
+                .product(name: "GRDB", package: "GRDB.swift"),
+                .product(name: "AnyLanguageModel", package: "AnyLanguageModel"),
+            ],
+            swiftSettings: [
+                .swiftLanguageMode(.v6),
+            ]
+        ),
+        .testTarget(
+            name: "SwiftDBAITests",
+            dependencies: ["SwiftDBAI"],
+            swiftSettings: [
+                .swiftLanguageMode(.v6),
+            ]
+        ),
+    ]
+)