refactor: decompose god-classes, add lint gates, restructure packages

- Decompose all 11 god-classes (>200 lines) into facade + collaborators
  (command/, schematic/, config/, generator/, mode/, papi/, adaptive/,
  storage/, player/, leaderboard/) — every file is now <=200 lines
- Add PMD 7 (report-only) + stricter checkstyle rules (NPath, IllegalCatch,
  NestedDepth, Whitespace, MissingOverride); fix real bugs found
  (printStackTrace, resource leaks in ConfigLoader/SQLStatsStorage)
- docs/ARCHITECTURE.md: target structure + 'one folder = one purpose' rule
- Pilot restructure: command/core|util/, mode/impl/solo|multi|barrier/,
  hook/papi/resolver/; cross-package classes made public
- TODO.md: track warning cleanup (132-138) + restructure progress

config/pmd/ruleset.xml

@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+
+<ruleset name="LoParkour PMD rules"
+    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+
+    <description>
+        PMD rules complementing checkstyle. Adds checks checkstyle does not
+        cover: resource leaks, string ==, empty control flow, god-class/size
+        hints and complexity.
+        Currently report-only; becomes a hard gate after the SRP refactor.
+        UnusedImports is excluded (handled by checkstyle).
+    </description>
+
+    <!-- ===== bugs / error-prone ===== -->
+    <!-- Empty if/while/finally blocks are covered by checkstyle (EmptyBlock,
+         EmptyStatement, EmptyCatchBlock); PMD 7 has no generic replacement. -->
+    <rule ref="category/java/errorprone.xml/EmptyCatchBlock"/>
+    <rule ref="category/java/errorprone.xml/UseEqualsToCompareStrings"/>
+    <rule ref="category/java/errorprone.xml/CloseResource"/>
+    <rule ref="category/java/errorprone.xml/UnusedNullCheckInEquals"/>
+
+    <!-- ===== dead code ===== -->
+    <rule ref="category/java/bestpractices.xml/UnusedPrivateMethod"/>
+    <rule ref="category/java/codestyle.xml/UnnecessaryImport"/>
+    <rule ref="category/java/bestpractices.xml/AvoidReassigningParameters"/>
+
+    <!-- ===== complexity ===== -->
+    <rule ref="category/java/design.xml/CyclomaticComplexity">
+        <properties>
+            <property name="methodReportLevel" value="15"/>
+        </properties>
+    </rule>
+    <rule ref="category/java/design.xml/CognitiveComplexity">
+        <properties>
+            <property name="reportLevel" value="15"/>
+        </properties>
+    </rule>
+
+    <!-- ===== god-object / size hints (mirrors the 200-line file rule;
+         line count itself is hard-gated by checkstyle FileLength) ===== -->
+    <rule ref="category/java/design.xml/GodClass"/>
+    <rule ref="category/java/design.xml/TooManyFields"/>
+    <rule ref="category/java/design.xml/TooManyMethods"/>
+</ruleset>