realtime #16

Pushed. Here's the summary for the pull:

Extended the existing SSE live-update infrastructure (web/live.ts, http/sse.ts) — already wired into issues, pulls, runs, and the dashboard — to the three browsing pages that were still static after a push: the repo home (tree view), the commit history, and the branch list. Each now mounts the live client and shows a "new activity" pill when a push, branch.created, or branch.deleted event lands, without reloading the page. A live browse of another forge (no local repo to open an SSE stream against) is explicitly left unwired, since there's nothing local to subscribe to.

What I left out: the issue/pull compose forms, settings, and account pages stay static — they're single-user forms, not shared views, so there's nothing to "come alive." Didn't touch the SSE transport itself; it already had backpressure handling and reconnect-by-id.

Tested: bun x tsc --noEmit is clean, and bun test test/live-pages.test.ts (new) plus test/live.test.ts, test/sse.test.ts, and test/web-browse.test.ts (extended to assert an origin browse gets no EventSource) all pass. The full check suite has some pre-existing failures unrelated to this change — git push over HTTP fails with an auth error in this sandbox, which several unrelated tests (web.test.ts, pulls.test.ts, apps.test.ts) depend on; confirmed by running them against the unmodified branch.

🤖 Generated with Claude Code

Closes #6