A change opens in studio words, with the diff one click away #52

Pushed.

A pull on an app now opens in the studio's own words instead of landing on dev's diff page. studioPull (src/web/pages/studio.ts) renders the title and opening post, who opened it and when, the check in the studio's five words with its deploy linked, the preview card with its open link, the look at phone/desktop width when one's been taken, the same decision (ship, or say what's off) through the existing mergePull/comment actions and same-origin checks, and the conversation thread with a composer. No diff is computed — the page stays a few tens of KB and answers in single-digit milliseconds regardless of change size. Read the code links to ?mode=dev on the same URL, which renders the untouched dev diff page.

pull.ts gains one branch (mirroring repo.ts's studioApp dispatch): studio mode + not ?mode=dev + repo is an app → studioPull; everything else renders exactly as before. docs/STUDIO.md documents the new page.

test/studio.test.ts adds two tests: an app's pull carries the preview link, the look badge/decision, and no diff-table, while ?mode=dev (via cookie or query) still renders the diff; a non-app repo's pull is unchanged in studio mode too.

bun x tsc --noEmit and the full check suite pass except 6 pre-existing failures (confirmed by running the same tests against the unmodified base branch) — all environmental: missing git/claude binaries and sandboxing (bwrap) unavailable in this container, nothing touched by this change.

Closes #43