v2: Initial clean branch with unit tests + CI/CD pipeline

- Started from ac75faa (initial E4B-MarkBase integration)
- Kept Sources/ (all engine code) + Package.swift + .gitignore
- Removed all ad-hoc tests, documentation, scripts, Python files
- Added Tests/00_Unit/ (MathTest, TokenizerTest, SamplerTest)
- Added .gitea/workflows/ci.yaml (build + unit tests + lint)
- Added Scripts/check_resources.sh (memory-aware test runner)
- Added Tests/Manifest.json (resource requirements for all tests)
- Focus: 4-bit quantized models only

Tests/00_Unit/SamplerTest.swift

@@ -0,0 +1,96 @@
+import XCTest
+@testable import MarkBase
+
+final class SamplerTest: XCTestCase {
+
+    var sampler: Sampler!
+
+    override func setUp() {
+        super.setUp()
+        sampler = Sampler()
+    }
+
+    // MARK: - Top-K Sampling
+
+    func testTopKFilter() {
+        var logits = [Float](repeating: 0, count: 100)
+        logits[10] = 10.0
+        logits[20] = 9.0
+        logits[30] = 8.0
+
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 3, topP: 1.0)
+        XCTAssertTrue([10, 20, 30].contains(result),
+                      "Should sample from top-3 tokens (\(result))")
+    }
+
+    func testTopKZero() {
+        var logits = [Float](repeating: 0, count: 100)
+        logits[50] = 5.0
+
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 0, topP: 1.0)
+        XCTAssertGreaterThanOrEqual(result, 0)
+        XCTAssertLessThan(result, 100)
+    }
+
+    // MARK: - Temperature
+
+    func testTemperatureZeroGreedy() {
+        var logits = [Float](repeating: -10, count: 1000)
+        logits[42] = 20.0
+
+        let result = sampler.sample(logits: logits, temperature: 0.0, topK: 1, topP: 1.0)
+        XCTAssertEqual(result, 42, "Temperature 0 should always select highest logit")
+    }
+
+    func testTemperatureHigh() {
+        var logits = [Float](repeating: 0, count: 1000)
+        logits[0] = 100.0
+
+        let result = sampler.sample(logits: logits, temperature: 10.0, topK: 100, topP: 1.0)
+        XCTAssertEqual(result, 0, "Overwhelming logit should still be selected")
+    }
+
+    // MARK: - Unused Token Filtering
+
+    func testFilterUnusedTokens() {
+        var logits = [Float](repeating: 0, count: 262144)
+        logits[258123] = 30.0
+        logits[500] = 29.0
+
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 50, topP: 0.95, filterUnusedTokens: true)
+        XCTAssertLessThan(result, 258000, "Should not sample unused tokens when filtering enabled")
+    }
+
+    func testNoUnusedTokenFilter() {
+        var logits = [Float](repeating: 0, count: 262144)
+        logits[258123] = 50.0
+        logits[500] = 0.0
+
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 10, topP: 1.0, filterUnusedTokens: false)
+        XCTAssertEqual(result, 258123, "Should allow unused tokens when filtering disabled")
+    }
+
+    // MARK: - Edge Cases
+
+    func testAllSameLogits() {
+        let logits = [Float](repeating: 1.0, count: 1000)
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 100, topP: 1.0)
+        XCTAssertGreaterThanOrEqual(result, 0)
+        XCTAssertLessThan(result, 1000)
+    }
+
+    func testSingleToken() {
+        let logits: [Float] = [5.0]
+        let result = sampler.sample(logits: logits, temperature: 1.0, topK: 1, topP: 1.0)
+        XCTAssertEqual(result, 0)
+    }
+
+    func testExtremeTemperatureZero() {
+        var logits = [Float](repeating: -100, count: 100)
+        logits[7] = 50.0
+
+        // Greedy: temperature=0, topK=1
+        let result = sampler.sample(logits: logits, temperature: 0.0, topK: 1, topP: 1.0)
+        XCTAssertEqual(result, 7)
+    }
+}