Documented "Pin Tab" feature is missing from the implementation

[mackenzieclark]

Summary

docs/docs/tabs.mdx:46 describes a Pin Tab feature in detail (right-click → Pin Tab, X button replaced with a pin icon, drag-to-reorder pinning behavior, etc.), but in the current build (0.14.5) the feature does not exist. The docs and the code are out of sync.

Evidence

The actual right-click context menu is built in frontend/app/tab/tabcontextmenu.ts. The full set of menu items implemented there:

• Tab Bar Position (submenu)
• Rename Tab
• Copy TabId
• Flag Tab (color flag submenu)
• Backgrounds (submenu)
• Close Tab

No Pin Tab / Unpin Tab entry. Greppping the entire tab folder for "pin" turns up exactly one match: a leftover CSS class .pinned-tab-spacer in frontend/app/tab/tabbar.scss:36 with no callers. No isPinned, no pin RPC, no pin meta key on the tab. Looks like the feature was either never landed or was removed and the docs weren't updated.

Request

Either:

1. Land the feature as described in the docs — which would be genuinely useful for users scaffolding many tabs (e.g. one per repo) who don't want to accidentally close them with a stray X click.
2. Remove the section from the docs so users don't go hunting for a menu option that isn't there.

Option 1 is the right answer for users; option 2 is at minimum required to stop the bleeding.