fix(perc-content-explorer): clear PSFolderDialog residual Xlint (#2441)

[natechadwick-intsof]

Summary

Clears the 5 residual -Xlint diagnostics on PSFolderDialog left after the #2380 panel rawtypes PR (#2438).

Diagnostic	Fix
this-escape	Class made final (no subclasses); early setResizable(true) removed — still applied in initDialog() after full field init
serial (×4 non-serializable collaborators)	m_parentFolderNode, m_folderNode, m_folderMgr, m_userInfo marked transient; m_applet also transient
serialVersionUID	Already present

No product behavior change. Prefer real fixes over class-level suppress. Structural tests in PSFolderDialogTest.

Parent / links

• Fixes [8.2] perc-content-explorer: PSFolderDialog residual warnings (#2380/#2045) #2441
• Parent module tracker: [8.2] Resolve javac warnings in perc-content-explorer module #2045
• Parent monorepo tracker: [8.2] Resolve all javadoc and javac errors and warnings #2200
• Residual of: [8.2] perc-content-explorer: PSFolder* UI panels rawtypes residual (#2369/#2045) #2380 / PR fix(perc-content-explorer): PSFolder* UI panel Swing rawtypes (#2380) #2438
• Out of scope: PSFolderAclEditorDialog ([8.2] perc-content-explorer: PSFolderAclEditorDialog rawtypes residual (#2380/#2045) #2439)

Test plan

• Erlang self-review approve — docs/ai-generated/code-reviews/issue-2441-psfolderdialog-xlint-erlang.md
• Standalone module clean install:
  cd modules/DesktopContentExplorer ../../mvnw.cmd clean install
  BUILD SUCCESS — Tests run: 54, Failures: 0 (includes PSFolderDialogTest ×3)
• Direct javac -Xmaxwarns 5000 on PSFolderDialog.java: 5 → 0 warnings
• No new warnings attributable to this change (baseline shade/dependency-analyze only)

Gates

• Pre-PR Maven verification: standalone perc-content-explorer clean install green
• Cross-platform paths: N/A (no path/file I/O)
• Operator: Grok: night-issue-prs (model grok-4.5)

Co-Authored by Grok Build using grok-4.5 with agent main.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (3 files)

• docs/ai-generated/code-reviews/issue-2441-psfolderdialog-xlint-erlang.md
• modules/DesktopContentExplorer/src/main/java/com/percussion/cx/PSFolderDialog.java
• modules/DesktopContentExplorer/src/test/java/com/percussion/cx/PSFolderDialogTest.java

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_{Reviewed by step-3.7-flash · Input: 49.8K · Output: 6.4K · Cached: 369K}

_{Review guidance: REVIEW.md from base branch main}