Seed security knowledge corpus (16 articles + 30 AL samples)

Converts Jesper's existing AL security-review prompt into BCQuality seed
knowledge articles so the al-security-review leaf has a real corpus to
match against. Mirrors the performance seed phase.

Articles under microsoft/knowledge/security/ (16):
- Permission model: follow-least-privilege-in-permission-sets,
  use-indirect-permissions-for-elevated-access,
  use-inherent-permissions-to-grant-minimal-access
- Secrets: never-hardcode-secrets-in-al,
  use-isolated-storage-for-module-and-company-secrets,
  prefer-azure-key-vault-for-production-secrets,
  use-secrettext-for-credentials, use-secrettext-with-httpclient,
  compose-secrets-with-secretstrsubstno,
  use-nondebuggable-when-parsing-secrets
- External calls: require-https-for-external-calls,
  set-timeouts-for-external-calls, do-not-put-credentials-in-urls
- Error handling: avoid-sensitive-data-in-error-messages,
  do-not-swallow-security-errors-silently
- Extensibility: do-not-expose-sensitive-data-in-event-publishers

Paired AL samples under samples/security/<slug>/{bad,good}.al, object
IDs 50200-50231 (no overlap with performance 50100-50140).

Rubber-duck findings addressed:
- HttpClient secret-URI: SetSecretRequestUri is on HttpRequestMessage
  (not HttpClient). Rewrote use-secrettext-with-httpclient and its
  good sample to use HttpRequestMessage + HttpClient.Send.
- InherentPermissions only grants access to same-extension objects;
  the sample now defines its own table 50230 "Sec Sample Lookup" and
  grants 'r' on that, not on Database::Customer.
- Reworked compose-secrets-with-secretstrsubstno bad.al away from
  Format(SecretText) (unreliable) to a plain Text+StrSubstNo anti-
  pattern.
- Moved normative guidance out of Description in three articles
  (compose-secrets-..., prefer-azure-key-vault-..., use-inherent-...)
  so it sits in Best Practice / Anti Pattern per READ contract.
- Added a companion helper codeunit (50231) to the indirect-permissions
  good sample so it actually demonstrates the controlled write path.
- Rebuilt the event-publisher good/bad pair on the same ExportCustomer
  scenario so the contrast is the shape of the event signature, not a
  different event.

Also: broaden samples/README.md object-ID range note to 50100-50299.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

microsoft/knowledge/security/prefer-azure-key-vault-for-production-secrets.md

@@ -0,0 +1,25 @@
+---
+bc-version: [26..28]
+domain: security
+keywords: [keyvault, azure, secrets, rotation, audit]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Prefer Azure Key Vault for production secrets
+
+> **Seed article.** Converted from an existing security-review prompt to bootstrap the BCQuality security corpus. Domain stewards should expand, restructure, and refine as needed.
+
+## Description
+
+Azure Key Vault is an external secret store that supports central management, rotation, and access auditing. The Business Central system application exposes integration APIs that retrieve Key Vault secrets at runtime. IsolatedStorage, by contrast, is a per-tenant local encrypted store with no central rotation or audit story.
+
+## Best Practice
+
+For production workloads that require secret rotation, access auditing, and separation between secret custodians and app developers, Azure Key Vault SHOULD be the store of record. Retrieve secrets into a SecretText variable on demand, cache only as long as the call requires, and never persist the retrieved plaintext anywhere the extension does not control. IsolatedStorage MAY be used when a per-tenant local encrypted store is all that is required.
+
+## Anti Pattern
+
+Treating IsolatedStorage as the long-term home for secrets in a multi-tenant production extension where secret rotation, central revocation, or access auditing are required.
+