feat(bash): resolve executor config through the bash settings namespace

The capability's namespace is owned by the seam because it names the
capability, not an implementation: a host composes exactly one provider of
ctx.bash, so both executor families register the same namespace with their
own schema and composition entry without ever colliding, and a settings
document carried between platforms keeps resolving on both.

Both executors read their config through a source thunk, so a stored change
reaches the next command. The constructor checks the schema cannot express
become the section validator, refusing a bad value at the write instead of
at the next command. pwsh re-resolves its executable only when the declared
path changed, so an unrelated settings change never re-probes the filesystem.

packages/bash/bash-local/package.json

@@ -27,6 +27,7 @@
   "peerDependencies": {
     "@deepseek-ai/dsh-bash": "^0.0.1",
     "@deepseek-ai/dsh-invariants": "^0.0.1",
+    "@deepseek-ai/dsh-settings": "^0.0.1",
     "@deepseek-ai/dsh-subprocess": "^0.0.1",
     "@deepseek-ai/dsh-timeout": "^0.0.1",
     "cordis": "^4.0.0-rc.7"
@@ -37,6 +38,7 @@
   "devDependencies": {
     "@deepseek-ai/dsh-bash": "workspace:^",
     "@deepseek-ai/dsh-invariants": "workspace:^",
+    "@deepseek-ai/dsh-settings": "workspace:^",
     "@deepseek-ai/dsh-subprocess": "workspace:^",
     "@deepseek-ai/dsh-subprocess-local": "workspace:^",
     "@deepseek-ai/dsh-timeout": "workspace:^",