feat(messages): list Mark unread above Copy message

[matt2e]

Why: I use mark unread the most and I think it is generally pretty common. Or atleast more so than copy message.

Summary

Moves the read-state toggle to the top of the message actions menu, so the menu reads Mark unread → Copy message → Send to channel → Edit → Delete → Report. Before this change, Mark unread/Mark read sat at the bottom of the management items, below Copy message.

• MessageManagement.tsx: splits the read-state toggle out of MessageManagementItems into a new MessageReadStateItem. A shared useManagedMessage hook keeps both on the same gate as before: a managed, delivered row in a writable channel.
• MessageActionBar.tsx: adds a leadingItems slot that renders above the built-in Copy message item.
• MessageRow.tsx: renders MessageReadStateItem in that slot.

Gating and toggle behaviour are unchanged. Only the item's position moves.

Screenshots

Message actions menu for an own thread reply in a writable channel, captured from the browser fixture (#alpha, light appearance, WebKit, 1440×950 viewport at 2x). The only difference is where Mark unread sits.

Before (5362dafa, main)	After (481f8279, this PR)

Tests

• New MessageRow test: the menu for a managed peer message lists Mark unread, Copy message, Report, in that order.
• MessageManagement tests now mount MessageReadStateItem next to MessageManagementItems.

Deferred checks

• Agent review and agent/human checks in the running app are still to do. The PR stays in draft until they're done.

🤖 Generated with Claude Code

[wesbillman]

No changes requested. The read-state item moves above Copy message while preserving the existing eligibility gate, toggle/error handling, and edit/delete focus handoffs; the updated tests cover peer/own menu order and keyboard-first-item behavior.

Star Lord automated source review via Wes’s account; head d7cc489c8e34c0c1395379b7790671797171a4e7, base b287b92860ad24d35c72989de146ce7f05a2dbb9. Source and both attached screenshots reviewed; no tests or app run here—hosted CI required/DCO passed, Windows validation was skipped, and runtime/human acceptance remains unverified.

[wesbillman]

One change needed: update the new menu-order test for the thread-follow contract introduced by the current base (inline). This is a test integration defect; the production read-state reorder still preserves the existing gate and handlers.

Star Lord automated source review via Wes’s account; head 19dcaf25e501c0ab759b43b7cf29450464f029ee, base 1ef9dcef3f7cfea3c550f73cd18494d5042f59d3. Source-only follow-up, including both attached screenshots; no tests or app run. JS/browser CI was still running at the single snapshot; runtime and human acceptance remain unverified.