feat(docs): complete P2.6 type safety cleanup and P2.7 system invariants

P2.6: Type Safety Cleanup
- Replaced 'any' return types in vite-plugin.ts with concrete types (UserConfig, transform return type)
- Documented TypeScript mixin 'any[]' exception in PlatformServiceMixin.ts
- Audit confirmed: zero 'any' in codebase except documented TS mixin limitation
- All external boundaries use 'unknown', all data payloads use 'Record<string, unknown>'

P2.7: System Invariants Documentation
- Created SYSTEM_INVARIANTS.md documenting all 6 enforced invariants
- Added to docs/00-INDEX.md under Policy & Contracts section
- Each invariant includes: What, Why, How, Where

Progress Docs Updates:
- Updated 00-STATUS.md: marked P2.6/P2.7 complete, added type safety invariant note
- Updated 01-CHANGELOG-WORK.md: added 2025-12-22 entries for P2.6/P2.7
- Updated 03-TEST-RUNS.md: added P2.6 type safety audit test run
- Updated P2-DESIGN.md: marked P2.6 acceptance criteria complete
- Updated SYSTEM_INVARIANTS.md: added Type Safety Notes section

Baseline Tag:
- Created v1.0.11-p0-p1.4-p1.5-p2.6-p2.7-complete

TypeScript compilation: ✅ PASSES
Build: ✅ PASSES
CI: ✅ All checks pass

ios/Tests/TestDBFactory.swift

@@ -0,0 +1,115 @@
+//
+//  TestDBFactory.swift
+//  DailyNotificationPluginTests
+//
+//  Created by Matthew Raymer on 2025-12-16
+//  Copyright © 2025 TimeSafari. All rights reserved.
+//
+
+import Foundation
+import SQLite3
+@testable import DailyNotificationPlugin
+
+/**
+ * Test database factory for recovery testing
+ * 
+ * Provides utilities to create test databases with intentionally invalid/corrupt data
+ * for testing recovery scenarios.
+ */
+class TestDBFactory {
+    
+    /**
+     * Create a clean test database
+     * 
+     * @return Tuple of (database, path)
+     */
+    static func createCleanDatabase() -> (DailyNotificationDatabase, String) {
+        let testDbPath = NSTemporaryDirectory().appending("test_recovery_db_\(UUID().uuidString).sqlite")
+        let database = DailyNotificationDatabase(path: testDbPath)
+        return (database, testDbPath)
+    }
+    
+    /**
+     * Inject invalid notification record directly into database
+     * 
+     * @param database Database instance
+     * @param id Notification ID (can be empty for invalid test)
+     * @param scheduledTime Scheduled time (can be invalid/negative)
+     * @param payloadJSON Payload (can be invalid JSON)
+     */
+    static func injectInvalidNotificationRecord(
+        database: DailyNotificationDatabase,
+        id: String = "",
+        scheduledTime: Int64 = -1,
+        payloadJSON: String = "invalid json {"
+    ) {
+        // Direct SQL injection for testing (using executeSQL which is public)
+        let escapedId = id.replacingOccurrences(of: "'", with: "''")
+        let escapedPayload = payloadJSON.replacingOccurrences(of: "'", with: "''")
+        let sql = """
+            INSERT INTO \(DailyNotificationDatabase.TABLE_NOTIF_CONTENTS) (
+                \(DailyNotificationDatabase.COL_CONTENTS_SLOT_ID),
+                \(DailyNotificationDatabase.COL_CONTENTS_PAYLOAD_JSON),
+                \(DailyNotificationDatabase.COL_CONTENTS_FETCHED_AT),
+                \(DailyNotificationDatabase.COL_CONTENTS_ETAG)
+            ) VALUES ('\(escapedId)', '\(escapedPayload)', \(scheduledTime), NULL);
+        """
+        database.executeSQL(sql)
+        print("TestDBFactory: Injected invalid notification record: id=\(id), time=\(scheduledTime)")
+    }
+    
+    /**
+     * Inject notification with null/empty required fields
+     */
+    static func injectNotificationWithNullFields(database: DailyNotificationDatabase) {
+        let sql = """
+            INSERT INTO \(DailyNotificationDatabase.TABLE_NOTIF_CONTENTS) (
+                \(DailyNotificationDatabase.COL_CONTENTS_SLOT_ID),
+                \(DailyNotificationDatabase.COL_CONTENTS_PAYLOAD_JSON),
+                \(DailyNotificationDatabase.COL_CONTENTS_FETCHED_AT)
+            ) VALUES (NULL, '', 0);
+        """
+        database.executeSQL(sql)
+    }
+    
+    /**
+     * Inject duplicate notification records (same ID, different times)
+     */
+    static func injectDuplicateNotifications(
+        database: DailyNotificationDatabase,
+        id: String,
+        times: [Int64]
+    ) {
+        for time in times {
+            injectInvalidNotificationRecord(
+                database: database,
+                id: id,
+                scheduledTime: time,
+                payloadJSON: "{\"title\":\"Test\",\"body\":\"Body\"}"
+            )
+        }
+    }
+    
+    /**
+     * Reset database (drop and recreate tables)
+     */
+    static func resetDatabase(database: DailyNotificationDatabase) {
+        database.executeSQL("DROP TABLE IF EXISTS \(DailyNotificationDatabase.TABLE_NOTIF_CONTENTS);")
+        database.executeSQL("DROP TABLE IF EXISTS \(DailyNotificationDatabase.TABLE_NOTIF_DELIVERIES);")
+        database.executeSQL("DROP TABLE IF EXISTS \(DailyNotificationDatabase.TABLE_NOTIF_CONFIG);")
+        // Recreate tables by opening a new connection
+        let _ = DailyNotificationDatabase(path: database.getPath())
+    }
+    
+    /**
+     * Clean up test database file
+     */
+    static func cleanupDatabase(path: String) {
+        let fileManager = FileManager.default
+        if fileManager.fileExists(atPath: path) {
+            try? fileManager.removeItem(atPath: path)
+        }
+    }
+}
+
+