Document get_filter_request_var()/gfrv() (int) cast rule

[TheWitness]

Summary

Adds a short note to .github/copilot-instructions.md under the Input Validation section: when
get_filter_request_var() (or its gfrv() shorthand) is called with only the $name argument,
it already validates the value as numeric, returns it as a string, and halts execution on
non-numeric input. So casting its output to (int) before using it only for string output
(print/echo/string concatenation) is redundant. This mirrors a rule adopted in
Cacti/plugin_flowview.

Test plan

Doc-only change; no code paths affected.

[Copilot]

🟢 Approval recommended

The doc-only change is scoped; the remaining changelog item is a minor nit.

Pull request overview

Documents the numeric validation and string-return behavior of get_filter_request_var()/gfrv().

Changes:

• Clarifies when (int) casts are redundant.
• Notes when numeric operations still require casting.

File summaries

File	Description
.github/copilot-instructions.md	Adds input-validation casting guidance.

Review details

Suppressed comments (1)

.github/copilot-instructions.md:88

• The repository guidance at .github/copilot-instructions.md:171 requires all changes to be recorded in CHANGELOG.md, but this documentation update has no corresponding changelog entry. Please add a --- develop --- bullet describing this rule so the project history stays complete.

`get_filter_request_var()` (and its `gfrv()` shorthand, where available) called with only the

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

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