round 1: project the web transcript from append-origin events

Replace the surface-ordered fold with a log-ordered human transcript:
append-origin surface events at their own log positions plus one marker per
landed compaction checkpoint. Command folding, the tool-call index, and the
rev-keyed memo carry over unchanged.

Removes foldDegraded, the padding sentinels, baseSeq, and degradedSeqs() --
they existed only to satisfy the core fold's seq === index assertion. That
also closes the pagination hole A1 exposed: a page can carry a checkpoint
whose shadowed range fell outside the window, and nothing resolves
surfaceOp.start anymore.

pnpm-lock.yaml

@@ -956,6 +956,9 @@ importers:
         specifier: ~4.4.7
         version: 4.4.7(@types/react@18.3.31)(immer@10.2.0)(react@18.3.1)
     devDependencies:
+      '@deepseek-ai/dsh-compact':
+        specifier: workspace:^
+        version: link:../../compact/compact
       '@deepseek-ai/dsh-invariants':
         specifier: workspace:^
         version: link:../../support/invariants