Add media, sponsorship, representation, and survey community policies

[khalyaro]

Summary

Adds four community-facing governance documents, all self-contained inside
Governance/community/. Each is a versioned policy with an owner, review
cadence, and change log, consistent with the existing Governance/ documents.

File	Covers
Governance/community/MEDIA_POLICY.md	Who speaks to media, the approval process, and messaging guidance.
Governance/community/SPONSORSHIP.md	Accepted sponsorship forms, conflict-of-interest rules, and transparency commitments.
Governance/community/REPRESENTATION.md	Who may represent the project, the approval process, and disclosure rules.
Governance/community/SURVEY_POLICY.md	How surveys are run, the privacy of responses, and how results are shared.

Scope

• Documentation only. No TypeScript, configuration, schema, or dependency is
  touched.
• All changes live under Governance/community/; nothing outside Governance/
  is modified.
• Governance/ is outside the Jest root and the TypeScript build, so no test,
  build step, or runtime path is affected.

Notes

• Regression tests are not applicable: this is a documentation-only change with
  no executable code.
• Cross-references point at existing and in-flight governance documents
  (BRAND_USAGE.md, RECOGNITION.md, roles/TREASURER.md,
  policies/TRANSPARENCY_REPORTS.md, compliance/SANCTIONS.md, EVENTS_POLICY.md,
  and others).

Closes #1869
Closes #1870
Closes #1871
Closes #1872

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