fix(detector): eliminate regex backtracking — resolve SonarCloud reliability gate

[aksOps]

Summary

Only 2 open bugs remained in new code (SonarCloud queried directly): both java:S5998 (MAJOR — reliability) in SqlMigrationDetector.java, same root cause as the 2 unreviewed java:S5852 security hotspots on adjacent lines. Fixing the regex addresses both rule families simultaneously.

Root cause

LQ_CREATE_TABLE_YAML and LQ_ADD_FK_YAML used a reluctant-outer quantifier (?:\s++[^\n]*+\n)*? to skip intermediate indented lines before the target key. The engine could backtrack through the reluctant *? on large input → quadratic/exponential runtime.

Fix

Negative-lookahead + possessive *+: intermediate lines that would match the target key (tableName / baseTableName / referencedTableName) are excluded up front, so the outer match terminates deterministically at the same point the reluctant version did. No semantic change for valid Liquibase YAML.

// Before
"createTable\\s*+:[^\\n]*+\\n(?:\\s++[^\\n]*+\\n)*?\\s++tableName\\s*+:..."

// After
"createTable\\s*+:[^\\n]*+\\n"
    + "(?:(?!\\s++tableName\\s*+:)\\s++[^\\n]*+\\n)*+"
    + "\\s++tableName\\s*+:..."

Tests

• 16 existing Liquibase-YAML tests still pass (positive case — plain changeSet with createTable + FK)
• +1 regression test: liquibaseYamlChangeSet_largeIntermediateContent_completesQuickly — 500-line pathological createTable block; detection completes in <1s post-fix (pre-fix would scale quadratically)
• Full suite: 17/17 in this class, BUILD SUCCESS

Expected gate impact

• new_reliability_rating C → A (both S5998 bugs resolved)
• new_security_hotspots_reviewed 97.5% → 100% (same regex patterns flagged by S5852 no longer match the vulnerable shape; if SonarCloud doesn't auto-clear them, they can be manually marked Safe in the UI with reference to this PR)

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate failed

Failed conditions
B Maintainability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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