fix(kb): lint and style cleanup pass — multi-product

[hilram7]

Summary

Cross-product lint and style cleanup pass on existing KB articles. Covers five
articles across two products and three KB categories.

Changes

Directory Manager — gMSA identity store connection error

• Fixed frontmatter: added missing kb tag, corrected product ID
  (directory-manager → directorymanager), expanded keywords from 5 to 11
• Fixed sidebar_label to include Error: prefix; updated first product
  mention to full name Netwrix Directory Manager
• Fixed 3× passive voice (Cause section, NOTE callout, Additional Notes)
• Changed error string formatting from bold to inline code
• Rewrote Cause section from colon-led bullets to a single paragraph
• Renamed ## Resolutions → ## Resolution; removed bold step-header pattern
  from numbered steps
• Added intro sentence to Symptom section
• Simplified Step 1 by folding placeholder note into the intro sentence;
  relabeled example table

Data Classification — NDC data encryption

• Fixed products frontmatter field: data_classification → dataclassification
• Removed leading and trailing whitespace from all body lines
• Fixed two passive voice constructions
• Added hyperlink to Netwrix Support in the closing NOTE

Data Classification — migration & maintenance articles

Applies Vale, Dale, and Derek fixes to three articles in the
migration-and-maintenance category.

• All three: added missing kb tag; corrected products field
  (data-classification → dataclassification); changed titles from "How to…"
  prefix to gerund form per KB style guide
• Migrating to Another Server: fixed truncated sidebar_label (shortened to
  "Migrating to Another Server"); added descriptive image alt text; linked
  "Install Netwrix Data Classification" in step 4 and Related Articles;
  service names moved from bold to inline code; prose fixes (wordiness, passive
  voice)
• Moving Indexed Files: defined NDC acronym on first use; fixed positional
  reference; capitalized sub-bullet list items; corrected forward slashes to
  backslashes in Windows paths; fixed invalid %Program Files% env var;
  split run-on step 4 sentence; paths on their own lines for readability
• Partially Rebuilding the DQS Index: introduced Netwrix Data
  Classification (NDC) in Overview; trimmed wordy Overview sentence

Testing

Local build passed (npm run start).

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Created via the in-development kb-pr-open Claude Code skill. Refs #1077.

Closes #1134