refactor(process): split the process manager out of the bash executor

New process/ capability family: @deepseek-ai/dsh-process owns ctx.processes —
abstract ProcessManager.spawn(spec) over a fully-explicit ProcessSpawnSpec —
plus the shared DSH_* managed-environment and CollectedOutput vocabulary;
@deepseek-ai/dsh-process-local carries the former bash-local run.ts plumbing
(detached groups, tail-keep spill-backed output, credential scrub, kill
escalation, kill-and-join disposal) with no config of its own.

dsh-bash-local becomes a consumer: it keeps command defaulting, the fused
deadline timedOut/aborted classification, the model-friendly terminal env
(now merged through the ordinary env channel), and the [stderr]-marked
background read merge, and spawns through ctx.processes. Background-process
lifetime moves to the manager, so an executor reload no longer kills live
background work; a background spawn failure is injected once into the read
path instead of being buffered as fake stderr. dsh-bash re-exports the moved
vocabulary so bash consumers keep one import root; dsh-bash-sandbox only
redeclares the inherited inject.

Every composition loading a bash executor now loads dsh-process-local (CLI,
examples, python bundled runtime, create-sdk bash feature, inline test
configs).

packages/bash/bash/src/types.ts

@@ -1,19 +1,17 @@
 /**
  * Execution types for the bash executor seam. Background task semantics belong
- * to `@deepseek-ai/dsh-tasks`; this seam exposes only process handles.
+ * to `@deepseek-ai/dsh-tasks`; this seam exposes only process handles. The
+ * managed-environment and captured-output vocabulary is owned by the
+ * process-manager seam and re-exported here so bash consumers keep one import
+ * root.
  * @module dsh-bash/types
  */
 
 import type { SandboxEnforcement, SandboxExecutionPolicy, SandboxMode } from '@deepseek-ai/dsh-sandbox'
+import type { CollectedOutput, DshEnvironment } from '@deepseek-ai/dsh-process'
 
-/** Namespace prefix reserved for DeepSeek Harness-managed child environment facts. */
-export const DSH_ENV_PREFIX = 'DSH_' as const
-
-/** One environment key inside the managed {@link DSH_ENV_PREFIX} namespace. */
-export type DshEnvironmentKey = `${typeof DSH_ENV_PREFIX}${string}`
-
-/** Trusted DeepSeek Harness variables for one bash execution. */
-export type DshEnvironment = Readonly<Record<DshEnvironmentKey, string>>
+export { DSH_ENV_PREFIX } from '@deepseek-ai/dsh-process'
+export type { CollectedOutput, DshEnvironment, DshEnvironmentKey } from '@deepseek-ai/dsh-process'
 
 /**
  * Sandbox facts for one run, present iff a sandboxing executor handled it.
@@ -110,16 +108,6 @@ export interface BashExecSpec {
   sandboxPolicy: SandboxExecutionPolicy | undefined
 }
 
-/** One captured stream: the (possibly truncated) text plus recovery info. */
-export interface CollectedOutput {
-  /** Collected text — the TAIL of the stream when truncated. */
-  text: string
-  /** True when bytes were dropped from `text`. */
-  truncated: boolean
-  /** Path to a file holding the COMPLETE stream, when truncated and available. */
-  spillPath?: string
-}
-
 /** The outcome of one completed (or killed) foreground run. */
 export interface BashRunResult {
   /** Exit code; null when the process died from a signal. */