fix: refine community skill install

[GatewayJ]

Summary

• Rename remote Skill Hub install wording to community install and remove source badges from Skill Hub lists.
• Show full community skill descriptions on hover/focus and link community skill rows to CSGHub.
• Let same-name community installs use Replace instead of a disabled state, with backend replace handling.

Validation

• go test ./internal/skill/local -run 'TestInstallArchive|TestInstallArchiveWithOptionsReplacesDuplicate' -count=1
• go test ./internal/api -run TestHandleSkillInstallFromOfficialHub -count=1
• pnpm exec vitest run tests/api/skills.test.ts tests/models/skillhub.test.ts
• pnpm exec vitest run tests/api/skills.test.ts tests/components/WorkspaceTabPanels.test.tsx tests/models/skillhub.test.ts -t 'remote skill|remote skills|skill hub helpers'
• pnpm exec tsc --noEmit
• pnpm exec eslint src/api/skills.ts src/models/skillhub.ts src/pages/WorkspacePage/components/WorkspaceSidebar/SkillUploadDialog.tsx src/pages/WorkspacePage/components/WorkspaceSidebar/WorkspaceTabPanels.tsx src/pages/HubPage/components/HubDetailPane/HubDetailPane.tsx tests/api/skills.test.ts tests/components/WorkspaceTabPanels.test.tsx tests/models/skillhub.test.ts
• git diff --check

Notes

• Full go test ./internal/api still hits existing TempDir cleanup failures in participant worker lifecycle tests.
• Full WorkspaceTabPanels.test.tsx still has an existing section-order assertion failure outside this change.