Add ProjectZomboidPerkLog (PerkLog.txt)

Per-line skill snapshot log; each Login event is paired with a perks
row containing comma-separated Skill=N tokens. PERK_PAIR regex extracts
each pair via preg_match_all for analyser use. Detectors: filename
match plus content signature on the unique '[Cooking=N, Fitness=N,
Strength=N,' prefix of the perks-row bracket.

src/Pattern/ProjectZomboid/PerkPattern.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Pattern\ProjectZomboid;
+
+/**
+ * Regex constants for the Project Zomboid PerkLog.txt format.
+ *
+ *   [time] [steamid][player][x,y,z][event-or-perks][Hours Survived: N].
+ *
+ * The fourth bracketed field is either a single token (Login, Logout,
+ * LevelUp, etc.) or a comma-separated list of Skill=N pairs. Both fit
+ * the same character class.
+ */
+class PerkPattern
+{
+    public const string LINE = '/^\[(\d{2}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3})\] \[\d{17}\]\[[^\]]+\]\[\d+,\d+,\d+\]\[[^\]]+\]\[Hours Survived: \d+\]\.$/';
+
+    public const string FIELDS = '/^\[\d{2}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3}\] \[(?<steamid>\d{17})\]\[(?<player>[^\]]+)\]\[(?<x>\d+),(?<y>\d+),(?<z>\d+)\]\[(?<event>[^\]]+)\]\[Hours Survived: (?<hours>\d+)\]\.$/';
+
+    public const string PERK_PAIR = '/(?<skill>[A-Za-z_]+)=(?<level>\d+)/';
+}