feat: Add VEX compact fixture and implement offline verifier for Findings Ledger exports

- Introduced a new VEX compact fixture for testing purposes.
- Implemented `verify_export.py` script to validate Findings Ledger exports, ensuring deterministic ordering and applying redaction manifests.
- Added a lightweight stub `HarnessRunner` for unit tests to validate ledger hashing expectations.
- Documented tasks related to the Mirror Creator.
- Created models for entropy signals and implemented the `EntropyPenaltyCalculator` to compute penalties based on scanner outputs.
- Developed unit tests for `EntropyPenaltyCalculator` to ensure correct penalty calculations and handling of edge cases.
- Added tests for symbol ID normalization in the reachability scanner.
- Enhanced console status service with comprehensive unit tests for connection handling and error recovery.
- Included Cosign tool version 2.6.0 with checksums for various platforms.

src/Findings/StellaOps.Findings.Ledger.WebService/Program.cs

@@ -25,6 +25,7 @@ using StellaOps.Findings.Ledger.WebService.Mappings;
 using StellaOps.Findings.Ledger.WebService.Services;
 using StellaOps.Telemetry.Core;
 using StellaOps.Findings.Ledger.Services.Security;
+using StellaOps.Findings.Ledger.Observability;
 
 const string LedgerWritePolicy = "ledger.events.write";
 const string LedgerExportPolicy = "ledger.export.read";
@@ -45,6 +46,8 @@ var bootstrapOptions = builder.Configuration.BindOptions<LedgerServiceOptions>(
     LedgerServiceOptions.SectionName,
     (opts, _) => opts.Validate());
 
+LedgerMetrics.ConfigureQuotas(bootstrapOptions.Quotas.MaxIngestBacklog);
+
 builder.Host.UseSerilog((context, services, loggerConfiguration) =>
 {
     loggerConfiguration