docs: add dynamic campaign scoping by entitlement tags

[c1-dev-bot]

Summary

• Documents the ability to filter campaign scope by risk level and compliance framework entitlement tags when selecting specific resources
• Adds tag filter documentation to both single campaign and campaign template creation flows
• Explains filter logic: OR within a single tag type, AND across tag types
• Documents dynamic scope re-evaluation for campaign templates — tag criteria are saved and re-evaluated at each campaign preparation, automatically including newly tagged entitlements
• Adds limitations: only built-in attribute types (risk level, compliance framework) are supported; custom tags are not supported for scoping
• Adds three new FAQ entries covering dynamic re-evaluation, mixing tag-based and manual scope, and supported tag types
• Cross-references entitlement attribute setup documentation
• Fixes a duplicate step in the campaign template flow

Test plan

• Verify that the new filter documentation in Step 3 (single campaign) accurately describes the UI behavior
• Verify that the new filter documentation in Step 3 (template) matches the single campaign version
• Verify the dynamic re-evaluation section accurately describes prepare-time behavior for templates
• Confirm that the FAQ entries are accurate and consistent with the feature behavior
• Verify cross-reference links resolve correctly (/product/admin/managing-entitlements#setting-entitlement-attributes)

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Automated PR Notice

This PR was automatically created by c1-dev-bot as a potential documentation update.

This documentation requires:

• Human review for accuracy and completeness
• Verification that it matches current product behavior
• Approval from the appropriate team before merging

[linear]

GOV-387 Write public documentation for dynamic campaign scoping by entitlement tags

[jessstarr-hub]

@mindymo - can you review this before noon tomorrow (3/6)?