fix: list conclusions workspace-wide instead of hard-coded "honcho" observer

[geertvanzoest]

Fixes #2

Problem

src/features/conclusions/hooks.ts hard-coded observerId = "honcho" and listed conclusions through honcho.peer("honcho").conclusions, sending {"filters":{"observer_id":"honcho","observed_id":"honcho"}}. On Honcho servers where the deriver stores conclusions under the observing peer itself (e.g. observer_id: "alice"), that filter never matches, so the Conclusions tab is permanently empty. The SDK's peer() get-or-create also silently created an empty honcho peer in the workspace just by opening the tab.

Changes

• useConclusionList now calls the workspace-level POST /v3/workspaces/{wid}/conclusions/list with an empty filter, so conclusions from every observer show up; the existing client-side observed-peer dropdown keeps working (it now actually gets populated).
• useDeleteConclusion goes straight to DELETE /v3/workspaces/{wid}/conclusions/{id} (no observer scope needed) — this also removes the peer-creation side effect.
• useConclusionSearch takes an explicit observerId/observedId, since the server requires an observer/observed scope for semantic search ("observer and observed must be specified for semantic search").
• Extracted getBaseUrl() in lib/honcho.ts (same DEV/localStorage logic getHoncho already used) for the raw API calls.

Testing

• npm run check and npm run lint pass.
• Verified against a self-hosted Honcho v3 instance: tab went from "No conclusions yet" to rendering all conclusions with correct Observer/Observed/Session metadata, pagination intact, delete working.

Supersedes #3.