feat(transport-http): GET /conversations/:id?sinceSeq= read-side history endpoint

Incremental rehydration endpoint for long-lived clients. Returns
ConversationHistoryResponse { chunks: StoredChunk[], latestSeq } — the RAW,
append-order, seq-filtered slice from conversation-store.loadSince, NOT
reconciled (reconcile conflicts with the per-chunk seq cursor, so it stays on
the turn path; the read path is a pure sync primitive).

- transport-contract: add ConversationHistoryResponse + StoredChunk re-export.
- transport-http: GET /conversations/:id route reaching the log directly via
  conversationStoreHandle (dependsOn conversation-store); pure parseSinceSeq
  (absent->0, invalid->400).
- build wiring: conversation-store dep + project ref.

FE Slice 2 backend prereq (read-side). typecheck clean, 481 vitest, biome clean.

1 files changed, 1 insertions, 0 deletions

diff --git a/bun.lock b/bun.lock
index 13a9e6c..b8f9bde 100644
--- a/bun.lock
+++ b/bun.lock
@@ -150,6 +150,7 @@
       "name": "@dispatch/transport-http",
       "version": "0.0.0",
       "dependencies": {
+        "@dispatch/conversation-store": "workspace:*",
         "@dispatch/credential-store": "workspace:*",
         "@dispatch/kernel": "workspace:*",
         "@dispatch/session-orchestrator": "workspace:*",