[Docs] Describe connector registry without claiming ingestion

[Chris0Jeky]

Problem

The shipped Integrations surface registers, lists, enables, disables, and deletes connector definitions, but no inbound connector execution path currently consumes registered webhook/clipper/import content or sends it through capture. The manual must not describe registry taxonomy as working ingestion.

Scope

• Re-prove the current IntegrationRegistryService and controller boundary.
• Describe /workspace/integrations as registry/management-only until ingestion is wired.
• Audit adjacent active user docs for the same present-tense ingestion claim.
• Keep existing standalone note-import/web-clip capture paths distinct from registered connector execution.

Acceptance criteria

• Active user documentation makes the registry-only boundary explicit.
• No shipped connector type is described as ingesting content unless an executable provider/worker/controller path proves it.
• Relevant local link and docs-governance checks pass.

Found during PR #1560 review: #1560 (comment)
Refs #1560.