feat(config)!: one ordering for configuration sources, and a bootstrap deny rule

$DSH_HOME/.env had just become an ordinary environment layer, which left the
harness resolving user-facing values from a flattened process.env that could
no longer say where a value came from. A key stored through the web page
stayed shadowed by an older key in the user's own .env. An endpoint could be
redirected by the project: the invoking directory's .env is materialized like
every other layer, and a base URL decides where a resolved API key is sent, so
a DEEPSEEK_BASE_URL written into a model-editable workspace would send the
user's credential — and the prompts carrying their code — to whatever host
that file named.

Give every user-facing value one ordering, with four kinds of source:

  explicit for this run     per-operation override, CLI argument
  > authored by deployment  --config / --config-replace
  > this launch's shell     inherited process environment
  > product-managed store   settings.yaml, .credentials.yaml
  > discovered file         $DSH_HOME/.env
  > defaults                schema default, shipped base, public default

The domains differ only in which tiers exist. The earlier split — credentials
ranking the environment over the managed file while settings ranked over the
environment — was inconsistent: the distinguishing fact is who authored the
source, not the domain.

packages/util/environment owns an immutable snapshot with per-layer
provenance. getFrom(name, sources) searches only the layers a caller names,
and omitting one is a refusal rather than a demotion: the adapters ask for
['process', 'user-env'], so no reordering can let a project file back into a
decision it was excluded from.

isBootstrapOnly rejects, before anything is materialized, any .env setting a
variable that governs how a process launches (PATH, SHELL, NODE_OPTIONS,
LD_PRELOAD), where code or model-visible instructions load from (the whole
DSH_* namespace, HOME, XDG_*), or how the network is reached (proxy and CA
variables). The namespace is denied wholesale so a switch added later cannot
become settable by being forgotten, and there is no opt-out.

verify-config-source-ownership keeps both rules: no unregistered process.env
read under packages/*/*/src (26 allowlisted with reasons), and no apiKey,
baseURL, or headers inlined from the environment in shipped Cordis config —
removing those inlines is what makes the deployment tier meaningful.

apps/cli/src/web.ts

@@ -12,6 +12,7 @@ import { addHarnessSourceSection, resolveConfigPath } from '@deepseek-ai/dsh-app
 import type {} from '@deepseek-ai/dsh-host-webserver'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 import type {} from '@deepseek-ai/dsh-tool-bash'
+import type { EnvironmentSnapshot } from '@deepseek-ai/dsh-environment'
 import { AppCLIEntry } from './app-cli-entry.ts'
 
 // The shared core every `dsh` surface mounts, plus this surface's overlay over it.
@@ -85,6 +86,7 @@ export function prepareWebRuntimeContext(ctx: Context, sourceRoot: string, mode:
 /**
  * Serve the browser UI from the shipped config tree. `host`/`port` are passed
  * through only when the flag was given; absent, the shipped Web overlay value stands.
+ * @param environment - this run's frozen environment snapshot.
  * @param host - the bind host, or `undefined` to keep the config default.
  * @param port - the listen port (`0` requests an OS-assigned port), or `undefined` to keep the config default.
  * @param dev - mount the client HMR receiver; `pnpm run dev:web` separately rebuilds watched plugin bundles.
@@ -95,6 +97,7 @@ export function prepareWebRuntimeContext(ctx: Context, sourceRoot: string, mode:
  * personal overlay; already parsed from `--config`.
  */
 export async function runWeb(
+  environment: EnvironmentSnapshot,
   host: string | undefined,
   port: number | undefined,
   dev: boolean,
@@ -104,6 +107,7 @@ export async function runWeb(
 ): Promise<void> {
   const mode: WebMode = dev ? 'development' : 'production'
   const entry = new AppCLIEntry({
+    environment,
     configPath: BASE_CONFIG,
     overlayPath: WEB_OVERLAY,
     ...config !== undefined && { extraOverlayPath: resolveConfigPath(config, undefined) },