v0.2.1 — post actions and images fixed

Fixes the three problems reported against v0.2.0.

Post actions were unclickable. The row of five actions plus the earnings readout overflowed a 360dp phone by 162 pixels, and anything that overflows in Flutter is clipped and stops receiving taps — so like, branch and bookmark were dead. Counts are now abbreviated (1.2k), padding is tighter, and the earnings block scales down instead of pushing the row off-screen.

Images were missing in the meme library, market collections, and NFT art. Three of the four reference shapes Twetch uses were resolving to the wrong URL:

reference	why it failed
b://<txid>@1	the output index was dropped, and <txid>.jpg answers with a one-byte body
/v1/media/…	the meme library returns API-relative paths that cannot be fetched as-is
<txid>.png	collection art is a txid with an extension and lives on the ordinals CDN

The resolver now matches the web client, and each reference produces a candidate list so art that was never mirrored onto api.twetch.com falls through to ordfs.network and media.ordinalswallet.com.

Sales and listings kept working throughout because those use a bare txid, the one shape that was already correct.

Verified by tests rather than by eye: a widget test taps every action at 360dp and asserts the row fits at 320dp, and a live test fetches a real reference of each shape from the API and asserts an actual image comes back.