1.0: Fix repo commands: edit data loss, JSON shape and remote safety #1325

Goal: repo commands change only what they are asked to change, report consistent JSON, and handle names and URLs safely.

• major: repo edit erases description, website and spindle when their flags are omitted. src/cmd/repo/write.rs:789-812, 888-915.
• minor: repo fork help says the fork lands on the upstream's knot. src/cmd/repo/mod.rs:75-77.
• minor: repo delete --json reports a uri for a missing declaration and in dry runs. src/cmd/repo/write.rs:1069-1070, 1122-1133.
• minor: --spindle rejects the did:web form. src/cmd/repo/write.rs:985-990.
• minor: The delete-branch guard exits 1 on a retryable read failure. src/cmd/repo/branch.rs:368-376, 399-407.
• minor: browse --pr makes up a pull URL for an issue or a missing ticket. src/cmd/browse.rs:62-69.
• minor: The SSH login name comes from the cached handle. src/cmd/repo/checkout.rs:681, 1004, src/cmd/repo/remote.rs:118.
• minor: repo list --limit help is a run-on about pulls. src/cmd/repo/read.rs:37-44.
• minor: repo list --json omits repo_did, and name is the rkey. src/cmd/repo/read.rs:56-59, 84-107, 269-294.
• minor: repo list and repo view report different created_at. src/cmd/repo/read.rs:101-105, 480-483.
• minor: repo collaborators sorts timestamps as strings. src/cmd/repo/collaborators.rs:110-114.
• minor: An account DID given to repo reads is not classified. src/clients/tangled/resolve.rs:739-747, src/cmd/browse.rs:88-95.
• minor: repo edit and repo delete reject --repo. src/cmd/repo/write.rs:666, 1040.
• minor: repo configure and repo fork print remote URLs with credentials. src/cmd/repo/checkout.rs:1111-1149, src/cmd/repo/fork.rs:233-236, 353-356.
• minor: repo list unit tests use an old sh.tangled.repo fixture. src/cmd/repo/mod.rs:837-879.