Fix connected IPNS version pruning

[magiccodingman]

What changed

Fixes the narrow watched-IPNS retention issue where TGP pointer versions and their -connected application folders were not interpreted as one version pair when Keep Old was disabled.

Pair-aware retention

The updater now parses both managed forms through one shared model:

name-vNNN
name-vNNN-connected

The same parser is used for latest-version discovery, next-version allocation, and retroactive pruning so the worker has one consistent version model.

Safe pruning

When old versions are pruned, TruthGate now:

• groups the pointer folder and connected application folder by version
• retains the newest version that has a pointer folder
• removes both MFS paths for each historical pair
• resolves the historical target CID from the connected folder first
• falls back to tgp.json.current when no connected folder is available
• retains compatibility with the former .tgp-meta.json TargetCid sidecar
• avoids unpinning a CID still used by the retained version
• handles orphan historical -connected folders without allowing them to determine the active version

This protects the case where two pointer versions reference the same application CID: pruning the older pointer must not remove the explicit pin still needed by the current version.

Tests

Adds focused unit coverage for:

• pointer and connected-name parsing
• rejection of unmanaged folder names
• pointer/connected version grouping
• next-version allocation
• pruning both historical folders
• preserving a target shared with the retained version
• orphan connected-folder cleanup
• TGP v1 current parsing
• legacy sidecar compatibility

Validation performed against the complete repository checkout:

dotnet restore TruthGate-IPFS.sln
dotnet restore TruthGate-Web/TruthGate-Web.Tests/TruthGate-Web.Tests.csproj
dotnet build TruthGate-IPFS.sln --no-restore --configuration Release
dotnet test TruthGate-Web/TruthGate-Web.Tests/TruthGate-Web.Tests.csproj --no-restore --configuration Release --filter "FullyQualifiedName~IpnsVersionRetentionTests"

The solution build and focused retention tests passed.

Scope

This PR changes only watched-IPNS version retention and its tests. It does not change PublishQueue, domain publishing, the TGP wire protocol, UI behavior, or Kubo garbage-collection policy.

[magiccodingman]

CI note for review:

• The solution restores and builds successfully in Release.
• The new IpnsVersionRetentionTests pass when run as the focused test class.
• Docker appliance and Docker repository-migration workflows are green.
• The existing TLS lifecycle tests workflow runs the entire TruthGate-Web.Tests project. Its full-project test command remains red after an identical rerun, despite the clean build and focused retention tests passing. On master, that project contains only the pre-existing CertificateLifecycleTests class; this PR adds the isolated retention class. I left the unrelated lifecycle behavior untouched rather than broadening this retention PR.