Fix static analysis blocker: bounds-guard m_directories in DpCatalog

[sympact06]

Related Issue(s)	#4521
Has Unit Tests (y/n)	n)
Documentation Included (y/n)	n
Generative AI was used in this contribution (y/n)	y

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Change Description

Clamp the loop bound in fillBinaryTree() to DP_MAX_DIRECTORIES so that
m_directories[dir] is provably in-bounds for the static analyzer.

Rationale

Resolves the SonarQube Blocker finding:

Line 399: Access of the field 'm_directories' at index 2, while it holds only 2 'class Fw::FileNameString' elements

Testing/Review Recommendations

No behavioral change the clamp is purely defensive

Future Work

Remaining non-blocker static analysis findings from #4521

AI Usage (see policy)

Claude Code (Anthropic, Opus 4.6) was used to:

• Analyze the static analysis finding and identify the root cause

First PR to fprime! Hope to contribute more and learn along the way

[timcanham]

Let's merge #4897 first.