feat(api): List + GetById usuarios — handlers, repo, endpoints [UDT-008]

src/api/SIGCM2.Application/Common/TempPasswordGenerator.cs

@@ -0,0 +1,43 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace SIGCM2.Application.Common;
+
+/// <summary>
+/// Generates cryptographically secure temporary passwords.
+/// Excludes visually ambiguous characters (I, O, l, o, 0, 1).
+/// </summary>
+public static class TempPasswordGenerator
+{
+    private const string UpperChars = "ABCDEFGHJKLMNPQRSTUVWXYZ"; // no I, O
+    private const string LowerChars = "abcdefghijkmnpqrstuvwxyz"; // no l, o
+    private const string DigitChars = "23456789";                  // no 0, 1
+    private const string SymbolChars = "!@#$%&*+-=?";             // copy-paste safe
+
+    private const string Charset = UpperChars + LowerChars + DigitChars + SymbolChars;
+
+    public static string Generate(int length = 12)
+    {
+        if (length < 8)
+            throw new ArgumentOutOfRangeException(nameof(length), "Password length must be at least 8.");
+
+        // SECURITY: NEVER log the result of this method
+        Span<byte> bytes = stackalloc byte[length];
+        RandomNumberGenerator.Fill(bytes);
+
+        var sb = new StringBuilder(length);
+        for (int i = 0; i < length; i++)
+            sb.Append(Charset[bytes[i] % Charset.Length]);
+
+        var result = sb.ToString();
+
+        // Guarantee diversity: at least 1 upper, 1 lower, 1 digit, 1 symbol
+        return HasDiversity(result) ? result : Generate(length);
+    }
+
+    private static bool HasDiversity(string pwd)
+        => pwd.Any(c => UpperChars.Contains(c))
+        && pwd.Any(c => LowerChars.Contains(c))
+        && pwd.Any(c => DigitChars.Contains(c))
+        && pwd.Any(c => SymbolChars.Contains(c));
+}

src/api/SIGCM2.Application/Common/Unit.cs

@@ -0,0 +1,7 @@
+namespace SIGCM2.Application.Common;
+
+/// <summary>Represents the absence of a meaningful return value.</summary>
+public readonly struct Unit
+{
+    public static readonly Unit Value = default;
+}