fix(cards): give a link-titled card a readable name at once - #81

Problem

Creating a card from a pasted GitHub link left the raw URL on screen, and people reloaded the page to get a readable name. Reported as: «когда пользователь копирует ссылку в название карточки она превращается в осмысленное название не сразу, а после перезагрузки страницы».

Two causes stacked up:

1. The create blocked on a GitHub round trip to fetch the item's title, so the optimistic card showed the URL for the whole request.
2. The client's optimistic card rendered exactly what was typed — the URL — until the response landed.

Fix

The create no longer waits on GitHub. It answers immediately under the same readable Pull: owner/repo#N fallback the server already used for unresolvable links, and a background pass fetches the real title and renames the card (measured on a dev board: fallback at once, real title ~1s later).

Two guards keep that honest:

• A person's words win: the background rename re-reads the card and only replaces the untouched fallback, so a card retitled meanwhile (by a human or an agent over MCP) is left alone.
• The creating tab actually sees it: watch frames echo-suppress against the originating client, which would have hidden the rename from the very person who created the card — until a reload, exactly as reported. Server-side work on nobody's behalf is now marked board.Unattributed, and the watch layer broadcasts it to everyone.

The client mirrors the same label (optimisticTitle, the TS twin of board.Link.FallbackTitle) in every optimistic card — Me zones, Team grid, weekly plan and both subtask forms — so the raw URL never shows, not even for the length of the create.

The background work is detached from the request (context.WithoutCancel + a 30s timeout), and its launch point is a swappable spawn so tests run it inline.

Testing

• TestCreateCardFromGitHubURL — create answers under the fallback, the background pass renames to the real title.
• TestCreateCardFromURLKeepsUserRename — a card retitled before the resolve lands keeps the person's wording; no rename call is made.
• TestUnattributedWorkIsNotEchoSuppressed — unattributed work carries no origin, so nothing is echo-suppressed.
• TestAPICreateCardFromGitHubURL — end-to-end over HTTP: instant fallback, then the resolved title.
• 4 new web tests for optimisticTitle (PR URL, issue URL, owner/repo#N shorthand, and leaving the user's own wording alone).
• Verified live on a dev board with both a public and a private repo link; full Go + web suites and golangci-lint pass.