feat: ✨ Show approved Agent configuration values - #79

Summary

• Add exact Agent allowlist entries for SQL parameter length, HTTP parameter and query string capture, Collector address, Agent name and Agent type.
• Require text values for the three named text settings. Keep current and default values redacted for other settings, including direct --key queries.

Refs #64

Verification

• ./gradlew --offline -Pcoverage=true coverageCheck verifyReleaseInputs passed on Linux. 228 tests, 95.51% line coverage and 80.23% branch coverage.
• Verified the six settings and their defaults in full and single-key queries against Collector 2.8.1 and Agent 2.21.3. Agent paths and hook patterns remained redacted. The wire test verifies password redaction and malformed text handling.