Seed performance knowledge corpus (22 articles + AL samples)

Converts an existing performance-review prompt into 22 atomic
knowledge articles under microsoft/knowledge/performance/, each
paired with AL samples under samples/performance/<slug>/ demonstrating
the anti-pattern and/or the best practice. The full set seeds the
corpus the microsoft/skills/al-performance-review leaf skill matches
against and validates the READ knowledge-file format end-to-end.

Every article conforms to the READ contract: six required frontmatter
fields, Description always present, no fenced code blocks, sample
code referenced by repo-relative path. Each article is marked with a
blockquote 'Seed article' note so domain stewards can extend or
restructure them freely.

Articles (ordered by concern area):

Database query efficiency
- use-findset-with-next (AA0181)
- avoid-findfirst-with-next (AA0233)
- only-fetch-records-you-use (AA0175)
- use-findset-readonly-by-default
- use-setloadfields-for-partial-records
- use-addloadfields-in-report-layouts
- use-calcsums-to-aggregate-filtered-sets (file: use-calcsums-for-flowfield-totals.md)
- avoid-calcfields-in-loops
- add-sift-keys-for-flowfields (AA0232)
- use-isempty-for-existence-checks

Filter and key optimization
- filter-before-find
- set-current-key-to-match-filters

Temporary tables and transactions
- use-temporary-tables-for-intermediate-data
- keep-transaction-scope-short
- avoid-user-interaction-in-transactions
- avoid-commit-inside-loops

Record operations
- prefer-get-for-primary-key-lookups
- use-insert-false-when-skipping-triggers
- prefer-direct-record-over-recordref

Strings, codeunits, events
- use-strsubstno-for-message-formatting
- use-single-instance-codeunits-for-caching
- keep-event-subscribers-lightweight

samples/README.md documents the sample-folder convention and makes
clear the samples are demonstration-only, not derived from BC base
application source, with unique object IDs in the 50100-50199 range.

Rubber-duck pass caught: a misleading good.al in avoid-calcfields-in-loops
(fixed by switching to a hoistable CalcFields scenario), an invalid
event subscriber signature in keep-event-subscribers-lightweight
(fixed by adding var xRec), normative guidance leaked into the
Description of use-findset-readonly-by-default (moved to Anti Pattern),
a missing sample pair for keep-transaction-scope-short (added), and
muddy FlowField/CalcSums framing (retitled and clarified).

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

microsoft/knowledge/performance/keep-transaction-scope-short.md

@@ -0,0 +1,29 @@
+---
+bc-version: [26..28]
+domain: performance
+keywords: [transaction, lock, scope, contention]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Keep transaction scope short
+
+> **Seed article.** Converted from an existing performance-review prompt to bootstrap the BCQuality performance corpus. Domain stewards should expand, restructure, and refine as needed.
+
+## Description
+
+Every write operation runs inside a transaction that holds locks until the transaction ends. Long transactions increase blocking, deadlocks, and timeouts for other sessions. The same work split across narrower transactions typically completes faster under load because it holds locks for less time.
+
+## Best Practice
+
+Perform data reads, calculations, and external integrations outside the transaction whenever possible. Enter the writing phase with all inputs computed, execute the minimum set of Insert, Modify, and Delete calls, and exit. If you have a long-running batch, split it into checkpoints at safe boundaries (see avoid-commit-inside-loops).
+
+See sample: `samples/performance/keep-transaction-scope-short/good.al`.
+
+## Anti Pattern
+
+Opening a transaction, then performing external web-service calls, heavy report runs, or user-facing dialogs while the locks are held, suspends every other session that needs the same rows for as long as the external operation takes.
+
+See sample: `samples/performance/keep-transaction-scope-short/bad.al`.
+