feat(ui): share the app bins' boot glue in @deepseek-ai/dsh-app-boot

The four near-twin helpers the two published bins carried — loadEnv,
installFailLoud, assertEntriesLoaded, boot — live once in
packages/ui/app-boot, parameterized by the bin's diagnostic prefix and
injectable at their side-effect seams (warn sink, process slice), so
every branch sits under the per-file 100% coverage gate: the unit suite
drives boot() in-process against the real Loader (relative-specifier
configs) through both the settled-tree path and the fiber-less-entry
rejection, and exercises the ENOENT/unloadable .env split, the
Error/non-Error/stackless fail-loud arms, and the disabled-entry
exclusion. resolveConfigPath (snapshot-aware) becomes the single path
resolver for both bins.

Each bin.ts is now a thin self-executing composition plus its
app-specific lifecycle (acp: replay env-skip + stdin-EOF dispose;
stdio: nothing extra), exports nothing, and stays coverage-excluded;
the built-bin smokes still prove both artifacts under plain node in the
node_modules-shaped temp dir (now symlinking ui/app-boot), including
the missing-config non-zero exit.

Implements docs/rfc/implemented/simplification/2026-07-04-share-app-bin-boot-glue.md
(moved from proposed/ and amended); the extract-example-app-packages
RFC's bin-ownership facts are amended in the same change.

packages/ui/stdio-agent/tests/built-bin.e2e.ts

@@ -35,7 +35,7 @@ const stdioBin = join(repoRoot, 'packages/ui/stdio-agent/lib/bin.js')
 const dshPackages = [
   'core/agent-core', 'core/agent', 'core/session', 'core/system-prompt',
   'core/tools', 'core/agent-loop', 'llm/llm', 'bash/bash', 'bash/bash-local',
-  'bash/tool-bash', 'support/invariants',
+  'bash/tool-bash', 'support/invariants', 'ui/app-boot',
   'session-persistence/session-persistence',
   'session-persistence/session-persistence-jsonl', 'ui/stdio-agent',
 ]