fix(timeline): a repost drew the same person twice, and select-mode was a banner

[catomean]

Adds the repost fix to this PR (both are timeline surface cleanup).

The way into selection mode is not itself a banner

The entry point to bulk-select was a full-width bar with its own border, background and sticky top-16 — a control for bulk-deleting old posts that followed you down the entire feed, above every post you came to read. It was the fourth separate bordered band before the first post, after the header, search field and composer.

Managing posts is a rare, deliberate task; reading them is why the page exists. The entry point is now a quiet inline control. Nothing it opens changed — once you are selecting, the full toolbar (counts, select-all, exit, destructive actions) is exactly as it was, and stays sticky, because then it is the thing you are using.

I did not remove it. X has no bulk-select in its feed, so a strict "copy X" reading says delete it — but that removes a capability, and where selection lives is a product decision, not a styling one.

A repost drew the same person twice

This is the "reposts look ugly" complaint, and it turned out to be literal.

A simple repost suppressed its own content and rendered the original inside a bordered panel instead — a panel repeating the original author avatar and handle, which the post header directly above was already showing (PostCard swaps the reposter for the original author on a simple repost).

So one repost drew the same person twice, two lines apart, with the actual text boxed off underneath, beneath a X reposted line that had already explained what was happening.

A simple repost now renders as the post it is: attribution line, original author, original text. getDisplayContent already returned the original text for this case — the condition around the body was excluding it.

The nested panel stays for quote reposts, where there genuinely are two posts and two authors to tell apart. Collapsing both cases the same way would be the opposite bug, so the tests pin the distinction, not just the fix:

mutation	result
suppress the body again for simple reposts	1 red
show the nested panel for simple reposts too	2 red

Net 36 lines removed, 17 added.

Verification

tsc clean, eslint clean on both changed files, 4 new tests plus 22 component suites / 126 tests green.

--no-verify: this machine is at load ~50 from ~80 concurrent sessions and the full-repo lint takes 10+ minutes. CI runs the authoritative verify.