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.

tsconfig.client.json

@@ -36,6 +36,12 @@
     // client-side Context merges keep it out of the host program.
     { "path": "./packages/host/directory-picker-native" },
     { "path": "./packages/host/directory-picker-browse" },
+    // Test-only leaf: the client-runtime drift trap for the compaction
+    // checkpoint source reads the seam's canonical const. It may appear HERE
+    // but never in a packages/client/* package project — dsh-compact's root
+    // reaches dsh-session's root, whose Context merge declares the host
+    // `sessions: SessionStore` and collides with the client's `ISessions`.
+    { "path": "./packages/compact/compact" },
     { "path": "./packages/client/ui-slots" },
     { "path": "./packages/client/ui-primitives" },
     { "path": "./packages/client/web-react" },