Add SkillProgressionAnomalyAnalyser

Compares consecutive perks-snapshot rows per Steam ID and emits a
SkillProgressionAnomalyProblem for any single skill whose level gained
more than THRESHOLD_DELTA between two snapshots. Login/Logout/LevelUp
event rows are skipped via a perk-pair regex check on the bracketed
event field.

Threshold of 3 reflects PZ's slow leveling pace: typical session bridges
should not produce four-or-more level jumps in a single skill. The
constant is documented inline so operators can tune for modded XP
servers without touching analysis logic.

Synthetic fixture extended with a PlayerSuspect Steam ID carrying two
snapshots: Strength jumps 2 -> 10 (delta +8, triggers), Fitness jumps
2 -> 8 (+6, triggers), Maintenance jumps 0 -> 3 (+3, exactly at
threshold, does NOT trigger). The existing single-snapshot players
remain noise-free.

src/Analysis/ProjectZomboid/SkillProgressionAnomalyProblem.php

@@ -0,0 +1,107 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Analysis\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Analysis\InsightInterface;
+use IndifferentKetchup\Codex\Analysis\Problem;
+
+/**
+ * Problem emitted by SkillProgressionAnomalyAnalyser when a single skill
+ * gained more than the configured threshold between two consecutive
+ * snapshots of the same player. Coalesced by (Steam ID, skill).
+ */
+class SkillProgressionAnomalyProblem extends Problem
+{
+    private string $steamId = '';
+    private string $player = '';
+    private string $skill = '';
+    private int $fromLevel = 0;
+    private int $toLevel = 0;
+    private int $delta = 0;
+
+    public function setSteamId(string $steamId): static
+    {
+        $this->steamId = $steamId;
+        return $this;
+    }
+
+    public function setPlayer(string $player): static
+    {
+        $this->player = $player;
+        return $this;
+    }
+
+    public function setSkill(string $skill): static
+    {
+        $this->skill = $skill;
+        return $this;
+    }
+
+    public function setFromLevel(int $level): static
+    {
+        $this->fromLevel = $level;
+        return $this;
+    }
+
+    public function setToLevel(int $level): static
+    {
+        $this->toLevel = $level;
+        return $this;
+    }
+
+    public function setDelta(int $delta): static
+    {
+        $this->delta = $delta;
+        return $this;
+    }
+
+    public function getSteamId(): string
+    {
+        return $this->steamId;
+    }
+
+    public function getPlayer(): string
+    {
+        return $this->player;
+    }
+
+    public function getSkill(): string
+    {
+        return $this->skill;
+    }
+
+    public function getFromLevel(): int
+    {
+        return $this->fromLevel;
+    }
+
+    public function getToLevel(): int
+    {
+        return $this->toLevel;
+    }
+
+    public function getDelta(): int
+    {
+        return $this->delta;
+    }
+
+    public function getMessage(): string
+    {
+        return sprintf(
+            'Player %s (%s) gained %d levels of %s between snapshots (%d to %d).',
+            $this->player,
+            $this->steamId,
+            $this->delta,
+            $this->skill,
+            $this->fromLevel,
+            $this->toLevel
+        );
+    }
+
+    public function isEqual(InsightInterface $insight): bool
+    {
+        return $insight instanceof self
+            && $insight->getSteamId() === $this->steamId
+            && $insight->getSkill() === $this->skill;
+    }
+}