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.

python/sdk-runtime/src/deepseek_harness_runtime/runtime/cordis.yml

@@ -13,13 +13,12 @@
     workspaceContext:
       maxBytes: 65536
 
-# Stock DeepSeek adapters. Loading requires an API key; initialize and shutdown
-# may use a dummy key because they do not call the model.
+# Stock DeepSeek adapters. The adapter resolves DEEPSEEK_API_KEY through the
+# credential seam and, with no provider mounted here, from the launching
+# environment; DEEPSEEK_BASE_URL follows the same environment ladder. Neither
+# is inlined, so this file names no secret and no route.
 - id: llm-deepseek
   name: '@deepseek-ai/dsh-llm-deepseek'
-  config:
-    apiKey: !!js process.env.DEEPSEEK_API_KEY
-    baseURL: !!js process.env.DEEPSEEK_BASE_URL
 
 # JSONL persistence; $DSH_SESSION_ROOT wins over ./.sessions in the process cwd.
 - id: sessions