[No QA] Add CLEAN-REACT-PATTERNS-6: guard wrappers for conditional subtrees

[adhorodyski]

Explanation of Change

Adds a new coding standard rule CLEAN-REACT-PATTERNS-6 — "Use guard wrappers to bypass feature subtrees".

The rule describes a pattern where a cheap guard component sits at the root of a feature subtree and decides whether to activate the feature or bypass it entirely. When bypassed, nothing below the guard mounts — no providers, no Onyx subscriptions, no Pusher connections, no effects. When activated, all feature logic is owned in one place (or a focused inner gate).

Two variants are documented:

• Single-level guard: condition check and feature logic in one component. Use for simple features.
• Two-level guard: cheap outer check short-circuits before a heavy inner gate ever mounts. Use when feature logic involves multiple subscriptions, Pusher, or complex state.

The rule includes real examples from PRs #85535 (AgentZeroStatusProvider) and #86543 (LinkedActionNotFoundGuard, ReportNotFoundGuard), wrong patterns (unconditional providers, scattered condition checks, prop drilling), review metadata, and "DO NOT flag if" guardrails to avoid over-applying the pattern.

Also updates the coding-standards SKILL.md index to list the new rule.

Fixed Issues

$
PROPOSAL:

Tests

• Verify that no errors appear in the JS console

Offline tests

N/A

QA Steps

Same as tests

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
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• I included screenshots or videos for tests on all platforms
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  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
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Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari