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-doc-graphs.ts

@@ -59,6 +59,7 @@ const GROUP_ORDER = [
   'llm',
   'core',
   'goal',
+  'process',
   'bash',
   'pty',
   'sandbox',
@@ -264,6 +265,15 @@ const SERVICE_ROLES: ServiceRole[] = [
     mode: 'core',
     note: 'Folds revisioned objective state from the session log and keeps live continuation activation process-local.',
   },
+  {
+    key: 'processes',
+    pkg: 'process',
+    title: 'Process manager seam',
+    mode: 'seam',
+    implementations: ['process-local'],
+    consumers: ['bash-local', 'bash-sandbox'],
+    note: 'The bash executors spawn their process groups through ctx.processes; the manager owns group lifetime, bounded spill-backed output, and kill escalation.',
+  },
   {
     key: 'bash',
     pkg: 'bash',