chore: Tune code scanning tools to reduce noise

[joshsmithxrm]

Summary

Code scanning tools are generating excessive noise on PRs. Need to tune or disable unhelpful rules.

Current Noise (from PR #227)

CodeQL (github-advanced-security)

• "Generic catch clause" - flags catch (Exception ex) (14+ instances)
• "Missed opportunity to use Where" - LINQ style suggestion

Copilot

• "This foreach loop implicitly filters its target sequence - consider filtering the sequence explicitly using '.Where(...)'"

Gemini

• Provides useful feedback (medium priority issues) - keep enabled

Actions

• Disable CodeQL "Missed opportunity to use Where" rule (cs/linq-use-where)
• Disable Copilot LINQ style suggestions if possible
• Review "Generic catch clause" warnings - some valid, some intentional
• Document decisions in .github/CODE_SCANNING.md

Context

Per ADR-0024 (pending), we prefer explicit foreach over LINQ. These style suggestions contradict that decision.

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🤖 Generated with Claude Code

[joshsmithxrm]

Resolved in this session:

Part 1: Cleared CodeQL noise

• Updated .github/codeql/codeql-config.yml with query-filters to disable style rules
• Dismissed all 282 open alerts (all were style rules or test file grandfathered alerts)

Part 2: Configured bot instructions

• Created .github/copilot-instructions.md with architecture guidance
• Created .gemini/config.yaml and .gemini/styleguide.md with Dataverse/concurrency patterns

Part 3: Added Roslyn analyzers (PPDS.Analyzers)

• PPDS006: UseEarlyBoundEntities - flags string literals in QueryExpression
• PPDS012: NoSyncOverAsync - flags .GetAwaiter().GetResult(), .Result, .Wait()
• PPDS013: NoFireAndForgetInCtor - flags async calls in constructors without await

Documentation: .github/CODE_SCANNING.md

See commit for full changes.