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).

scripts/gen-tool-catalog.ts

@@ -19,6 +19,7 @@ import ToolRegistry, { type Config as ToolsConfig } from '@deepseek-ai/dsh-tools
 import { BashExecutor } from '@deepseek-ai/dsh-bash'
 import type { BashExecRequest, BashExecSpec, BashProcess, BashRunResult } from '@deepseek-ai/dsh-bash'
 import LocalBashExecutor from '@deepseek-ai/dsh-bash-local'
+import LocalProcessManager from '@deepseek-ai/dsh-process-local'
 import LocalFileSystem from '@deepseek-ai/dsh-fs-local'
 import UserInteractionService from '@deepseek-ai/dsh-user-interaction'
 import PlanModeService from '@deepseek-ai/dsh-plan-mode'
@@ -197,6 +198,7 @@ const TOOL_PACKAGES: ToolPackage[] = [
     requires: ['ctx.tools', 'ctx.bash', 'ctx.tasks at call time for run_in_background'],
     writes: ['tool/call', 'tool/result'],
     async mount(ctx) {
+      await ctx.plugin(LocalProcessManager)
       await ctx.plugin(LocalBashExecutor)
       await ctx.plugin(ToolBash)
     },