feat(tasks): implementation runs read steering notes and fleet memory

What Task runs that implement a signal report (Create PR press, autostart) should read the team's steering notes and the scout fleet's scratchpad before acting. Read-only, deliberately. Why An implementation run currently knows nothing the team has told the rest of the self-driving system — "this area is frozen until the migration lands", "always extend the existing test file in X", "PRs touching billing need a feature flag". Scouts and (with #91267) report research read that guidance; the stage that actually writes code does not. The reads are free: task sandboxes default to posthog_mcp_scopes="read_only" (products/tasks/backend/temporal/process_task/workflow.py), and signal_scout:read — which gates scout-notes-list / scout-scratchpad-search — is part of MCP_READ_SCOPES (posthog/temporal/oauth.py). So the tools are already callable; the run is just never told about them. Implementation sketch • Verify the scope posture act…