Merge branch 'code-runtime-worker' into code-mode-tools

Brings in the refreshed base (master merged through the stack after #203
and #205 landed), including the acp-snapshot extraction (#204), and
re-ports this PR's snapshot-suite extensions onto the extracted package:

- dsh-acp-snapshot's Scenario gains headerClass and configPath; the suite
  factory pins the request header PER CLASS (construction rejects a
  missing or duplicated class pin), forwards a scenario's configPath to
  the harness (RunOptions.configPath overrides AgentUnderTest.configPath),
  and a new fixtures meta-test asserts every pinning fixture carries
  exactly one request/header and no deltas.
- The acp-agent example's thin scenario table re-registers code-mode-turn
  and both-mode-turn with their overlay configs and per-class pins; the
  committed fixtures replay unchanged.
- The package's synthetic suites cover the new surface (explicit
  headerClass on one suite, the default on the other, a configPath
  override through the fake bin, and the two construction throws).

docs/config-catalog.md

@@ -889,6 +889,7 @@ Abstract service classes — a deployment loads a concrete implementation packag
 
 Imported as libraries by other packages; a `cordis.yml` cannot load them.
 
+- `@deepseek-ai/dsh-acp-snapshot` ([`packages/support/acp-snapshot/src/index.ts`](../packages/support/acp-snapshot/src/index.ts))
 - `@deepseek-ai/dsh-app-boot` ([`packages/ui/app-boot/src/index.ts`](../packages/ui/app-boot/src/index.ts))
 - `@deepseek-ai/dsh-brand` ([`packages/util/brand/src/index.ts`](../packages/util/brand/src/index.ts))
 - `@deepseek-ai/dsh-hook-protocol` ([`packages/hooks/hook-protocol/src/index.ts`](../packages/hooks/hook-protocol/src/index.ts))