Replace the custom /dsh-context RPC channel + 2s client polling with a native
contextTimeline session-projection unit: the host registers one pure
init/apply/view unit on ctx.sessionProjections (framework-driven, persisted by
the projection cache, streamed via session/projection push frames), and the
client reads the finished value through the framework standard
useProjection seat. Deletes the client stale-while-revalidate cache and the
local service type stubs; grows the modern shelf registration (locale) and
adds the published @deepseek-ai/* types as devDeps plus zod as the single
runtime dependency (wire schema, kept external in the host bundle).
Fixes tool-result node attribution to read the durable source.callId /
content toolCallId instead of the never-present block.callId (tool labels had
silently never rendered).
Retention is tightened to trim by whole turn-runs deterministically (bounded
state, no 1200<->1500 oscillation under incremental folding).
Tests now drive the projection unit directly (host) and feed the view through
a useProjection stub (client); all chart/render assertions preserved. Adds
docs/redesign.md (review + target architecture, phases 0-3 landed) and
docs/CLIENT_SURFACE.md (client-side audit).