[T-Crypt]

Stacked on #273. Merge that first; this PR's base then moves to next.

The harbor never showed claims. A game's hold appeared only as a claim: lease on the board, and an app that a track claim names, such as OBS or Blender, did not appear anywhere. You had to run berth claims to see what was holding the card or what memory had a name. The card tab now has a CLAIMS panel beside the stowaways.

What it shows

• Only the rules that match now. The panel head counts them ("2 active of 5 rules"), and idle rules are only counted.
• Hold rows. In amber, with the lease (holds the card as l-9; engines wait), or waiting for the card with the node's wait reason.
• Track rows. In cyan, with the card memory they name (0.6 GiB named, not a stowaway), plus GTT on an APU.
• Card names. On a machine with several cards each row names its card from the claim's cards, the same way stowaways do. With feat(claims): hold only the cards a claim's gpu names #272, a claim held only on gpu1 reads gpu1, HOLD.
• Empty states. "No game or app is claiming a card" when nothing matches, and "no claim rules" when the built-in pack is off and berth.toml has none.
• The section rail has a Claims link. The About tab's section on stowaways now covers claims and this panel.
• The demo fixture has an active OBS track claim and idle built-in rules.

The data was already in /v1/status, because the harbor forwards the node's whole status. No Go code changes.

Proof

• A Playwright script swaps in five fixtures and checks the panel text, 27 checks in all: the stock demo, two cards with a hold granted on gpu1, a hold that is waiting, every rule idle, and no rules. All pass, with no page errors.
• The 28 navigation checks from feat(harbor): rewrite the About tab and fix header clipping #273 pass on this branch.
• go build, gofmt, go vet, the Windows build and vet, golangci-lint (0 issues) and go test ./... all pass.
• CHANGELOG [Unreleased] and docs/harbor.md are updated.