TicketCard: make issue and PR links clickable using LinkChip (match session header)

[dhilgaertner]

Problem

In the ticket list (ticket board), each row shows the issue title and — if a PR exists — a small PR badge. Neither is clickable: there's no way to jump from a ticket row out to the issue or PR on GitHub.

Inside a session, we already have the pattern I want: small click-through capsules in the session header (Issue #123, PR link, Repo link) that open the URL in a browser. I'd like the same treatment on every row in the ticket board.

Expected

For each ticket row:

• A clickable Issue #N chip that opens the GitHub/GitLab issue URL
• A clickable PR #N chip that opens the PR URL — only when a PR is associated with the issue

Same visual style / interaction as the session-level chips for consistency.

Current Behavior

• Packages/CrowUI/Sources/CrowUI/TicketBoardView.swift → TicketCard (lines 378–587)
• The PR badge is rendered at line 413 via ticketPRBadge(number:url:) (lines 496–510), but it's a plain styled capsule — no tap handler, no NSWorkspace.shared.open.
• The issue URL (AssignedIssue.url) is not surfaced as a chip at all.

Reuse the Existing Component

LinkChip already exists and does exactly this — clickable capsule with icon + label that calls NSWorkspace.shared.open:

• Component: Packages/CrowUI/Sources/CrowUI/SessionDetailView.swift:360-389
• Usage in session header:
  • Issue chip: SessionDetailView.swift:96-101 — LinkChip(label: "Issue #\(...)", url: session.ticketURL, icon: "link")
  • PR chip: SessionDetailView.swift:105-107 — LinkChip(label: link.label, url: link.url, icon: "arrow.triangle.pull")

Data Already Available

Packages/CrowCore/Sources/CrowCore/Models/AssignedIssue.swift:

• url: String (line 9) — issue URL, always present
• prURL: String? (line 16) — PR URL when linked

No new fetching or model changes needed.

Proposed Fix

1. Make LinkChip accessible to TicketBoardView (move to a shared location in CrowUI if it isn't already, or extract to its own file).
2. In TicketCard, replace the non-clickable ticketPRBadge with a LinkChip for the PR (when issue.prURL != nil).
3. Add a second LinkChip for the issue itself using issue.url, so every row has at least the issue chip.
4. Match icon convention: "link" for issue, "arrow.triangle.pull" for PR.

Files Affected

• Packages/CrowUI/Sources/CrowUI/TicketBoardView.swift (replace ticketPRBadge, add issue chip in TicketCard)
• Packages/CrowUI/Sources/CrowUI/SessionDetailView.swift (possibly extract LinkChip if it's file-private)

Acceptance Criteria

• Every ticket row has a clickable issue chip
• Ticket rows with a linked PR also show a clickable PR chip
• Clicking either chip opens the URL in the default browser
• Visual style matches the session-header chips