fix(config): close the review findings on configuration source ownership

Two had real security consequences:

The bootstrap rejection ran on npm dotenv's parser while process.loadEnvFile
applied the file with Node's own. Two independently maintained dialects meant
the check and the thing it guards could disagree: a name Node accepts but the
checker misses would reach process.env unchecked, and BASH_ENV there runs a
file of the project's choosing on every `bash -c` the bash tool issues. Parse
once with node:util's parseEnv — the same engine loadEnvFile uses — and assign
the entries already checked, which also drops the dotenv dependency.

llm-pi-ai still returned a literal profile.apiKey ahead of everything, and it
registers a settings namespace, so the defect removed from llm-deepseek
survived intact in its design twin. The field is gone from the profile schema,
the resolution path, and the tests.

The rest are consistency and documentation defects the review named:

- verify-config-source-ownership did not scan the Python runtime's bundled
  cordis.yml, which still inlined apiKey and baseURL. Both are covered now, and
  the line-anchored INLINE_DENY documents that it is a tripwire, not a parser.
- The deny list missed NODE_TLS_REJECT_UNAUTHORIZED, the askpass hooks, the
  GIT_CONFIG_* redirections, and PYTHONHOME — all implied by its own stated
  rule about what a variable does.
- Snapshot lookups folded case on Windows, where environment names are
  case-insensitive and an exact-match Map could miss a higher-ranked layer.
- The credentials note claimed a read-time permission check was "not taken"
  while this PR implemented it; the credentials-local README still described
  two layers, live process.env reads, dotenv-era limitations, and a renamed
  anchor; the llm-deepseek README still advertised the removed literal apiKey;
  and web.ts and base.cordis.yml kept personal-overlay wording.
- The ownership note's literal-apiKey claim now names its scope: the
  web-search providers keep a literal field but register no settings
  namespace, so nothing can shadow a stored credential through them.

packages/llm/llm-deepseek/README.md

@@ -15,7 +15,6 @@ The package root exposes the Cordis plugin contract and `DeepSeekAdapter`; wire
   name: '@deepseek-ai/dsh-llm-deepseek'
   config:
     apiKeyEnv: DEEPSEEK_API_KEY  # default; resolved per request via ctx.credentials, then the environment
-    # apiKey: …                  # literal escape hatch; prefer the reference so no secret enters this file
     baseURL: https://api.deepseek.com # optional; $DEEPSEEK_BASE_URL then the public API when omitted
     thinking: enabled        # optional; provider default is enabled
     reasoningEffort: high    # optional; off | high | max — omitted ⇒ high
@@ -53,7 +52,7 @@ The same exact-model result exposes ordered `off`, `high`, and `max` efforts und
 Connection facts are not frozen at load. `resolveAdapterOptions` is the one explicit resolve step from raw config to validated facts, and the adapter re-reads them through a thunk **once per operation**: base URL, catalog, request defaults, and idle budget all take effect on the next request, while an in-flight stream keeps the facts it started with. Two optional seams feed that thunk:
 
 - **`ctx.settings`** — the plugin registers the `llm-deepseek` namespace with this same `Config` schema and its `cordis.yml` entry as the composition `base`, so a `llm-deepseek:` section in the user settings document overrides any field without a restart. Without a mounted settings service the entry config alone drives the adapter, unchanged. A live settings snapshot that passes the schema but fails a beyond-schema bound (a duplicate catalog id, a broken thinking/effort pair) keeps the last good facts and logs the failure; the entry config itself still fails plugin load.
-- **`ctx.credentials`** — the API key resolves per stream call, from the *same* resolved snapshot that supplies the endpoint: a non-empty literal `apiKey` wins, then `apiKeyEnv` through the credential seam (`$DSH_HOME/.env` under the live environment), then — only without a mounted seam — the raw environment variable. Because credential facts travel with the connection facts, a settings snapshot the resolver rejects contributes neither its endpoint nor its key: the whole previous generation keeps serving. A request with no key anywhere fails with `MISSING_CREDENTIAL` naming every configuration entry point, while the route stays registered and the catalog stays browsable — first-run onboarding is "browse models, store the key, prompt again", with no restart between.
+- **`ctx.credentials`** — the API key resolves per stream call, from the *same* resolved snapshot that supplies the endpoint. Configuration carries only `apiKeyEnv`, never a literal key: the reference resolves through the credential seam, and without a mounted seam through the trusted environment layers. Because credential facts travel with the connection facts, a settings snapshot the resolver rejects contributes neither its endpoint nor its key: the whole previous generation keeps serving. A request with no key anywhere fails with `MISSING_CREDENTIAL` naming every configuration entry point, while the route stays registered and the catalog stays browsable — first-run onboarding is "browse models, store the key, prompt again", with no restart between.
 
 The one registration-captured fact is the retry policy: when its resolved value changes, the plugin re-registers the route in place (same adapter instance, one synchronous section), so `ctx.llm.providerRetryPolicy('deepseek-official')` always reports the current policy.
 
@@ -112,7 +111,6 @@ Loop-retained response blocks append to the next request and preserve its earlie
 ## Known Limitations and Deferred Work
 
 - **A settings `models` list replaces the composition list wholesale** — settings-layer merging is per-field, and arrays are one field; per-entry catalog merging would need a keyed shape.
-- **`Config.apiKey` is redacted on the wire but still a stored literal** — `describe({ redactSecrets: true })` strips it and reports the slot, so a configuration UI never receives the value; the key is nonetheless stored in the settings document rather than the credential store, so prefer `apiKeyEnv`.
 - **`tool_choice` is not mapped** — not part of the core vocabulary (MVP cut, shared with the pi-ai twin).
 - **Requests use raw `fetch`, not `@cordisjs/plugin-http`** — no shared proxy/interception configuration; adoption is deferred until a second adapter wants it (`TODO(http)`).
 - **Serialization flattens user and tool-result content to text blocks** — plugin-added block types are skipped, and empty tool output crosses the wire as the literal `(no output)`.