[Story]: Filter Knowledge Base artifacts by GitHub org-level metadata

[adoLime]

User Story

As a PM or Admin, I want to filter the Knowledge Base artifact list for GitHub organization-level metadata (org profile, teams, and members), so that I can inspect an organization's structure and people separately from repository content like commits, issues, and pull requests.

Context & Motivation

• Type: Functional (Connectors & Artifact Ingestion — Frontend)
• Parent epic: 03 EPIC - Connectors & Artifact Ingestion #52 (03 EPIC – Connectors & Artifact Ingestion)
• Teams: team:frontend (primary)
• Builds on: [Story]: Ingest GitHub organization-level metadata (org profile, members, teams) #261 (Ingest GitHub organization-level metadata — Sprint 8), [Feature]: Org level metadata sprintstart-backend#167 (closed: backend already persists one ORG_METADATA artifact per connected org, with teams and members in its artifact metadata).

The backend already delivers ORG_METADATA artifacts, but the frontend's ArtifactType union and the Knowledge Base tab bar (ALL | UPLOADS | PR | ISSUES | FILES | COMMITS) don't know the type. Org artifacts therefore render under "All" without a dedicated icon, label, or way to isolate them.

In Scope

• New "Organization" filter tab in the Knowledge Base artifact filter bar
• Extend the frontend ArtifactType union with ORG_METADATA (type mapping, icon, display name)
• Org-aware rendering in the artifact viewer drawer (org profile: description, location, blog, repo counts; teams and members from artifact metadata)

Acceptance Criteria

• A filter tab "Organization" appears alongside the existing tabs and shows only GitHub ORG_METADATA artifacts when active.
• Org artifacts have a dedicated icon and display the organization name (not a generic/unknown label) in the artifact list.
• The artifact viewer drawer renders the org profile (description, location, blog, public/private repo counts) and lists teams and members from the artifact metadata.
• The filter combines correctly with the text search and pagination (same behavior as the existing tabs).
• Empty state when no org metadata has been ingested for the selected project.
• i18n (en/de), light/dark themes, keyboard-accessible tab bar (existing ArtifactFilters behavior).
• Unit tests for the filter logic (useKnowledgeBase) and the ORG_METADATA type mapping.

Technical Notes

• Frontend touchpoints: src/features/knowledge-base/tabs.ts (TABS, KnowledgeTab), useKnowledgeBase.ts (tab matching), types.ts (ArtifactType), ArtifactViewerDrawer.tsx, icon mapping.
• Backend contract is unchanged: ORG_METADATA is already served by the artifact endpoints.
• Granular sub-filters (separate ORGANIZATION / TEAM / MEMBER artifact types, as visioned in [Story]: Ingest GitHub organization-level metadata (org profile, members, teams) #261) are out of scope here — the current backend persists one org artifact; splitting it is backend work tracked in [Story]: Ingest GitHub organization-level metadata (org profile, members, teams) #261.

Sub-Tasks (by team)

• Frontend — extend ArtifactType + tabs + filter logic, org icon/label, viewer drawer rendering, i18n, unit tests.