chore(backlog): rewrite for OpenWatch Go; drop Python-era tasks

[remyluslosius]

Summary

Python tree (backend/, root frontend/) is FROZEN as of 2026-06-04 per CLAUDE.md (which is gitignored / local-only). BACKLOG entries that target the Python release are no longer actionable, and the file had not been updated since 2026-03-27 — well before the Go rebuild started landing real features.

What's removed

Section	Reason
PRD Epics E3 (Documentation), E5 (Testing), E6 (Production Hardening)	All complete-and-Python-era
"Recently Completed (2026-03-27)"	Itemized Python-era PRs
"Stretch Goals" (E5-G1..E5-G7)	Targeted Python backend / frontend coverage
"Security Assessment Remediation" (M-2, H-2)	Python login + refresh flows
Bug entries citing Settings.tsx, "OpenSCAP" frontend hints, Known Hosts wiring	Python frontend
Technical-debt items for owca/extraction/xccdf_parser.py, lxml, liveness ping port detection in liveness_tasks.py	All Python paths

What's added / reorganized

Section	Content
Recently Completed (2026-06-03/04 session)	Nine PRs from the SSH connectivity / discovery / host-detail / activity stack: #469, #470, #471, #472, #474, #475, #477, #478, #479
Active Work — Host Detail Overview tab (~90%)	Top failed rules + Compliance trend stubs; Open exceptions + Updates-pending placeholders
Active Work — Host Detail other tabs	Per-tab status (Compliance, Packages, Services, Users, Network, Audit log, Activity, Remediation, Terminal)
Activity Feed Follow-ups	Build out /hosts/{id}?tab=activity, SSE invalidation for host_activity, NULL→online filtering
OpenWatch OS Remaining Work	Go-applicable items only (Adaptive Scheduler, email/in-app notifications, dashboard customization)
OpenWatch+ Subscription	Unchanged — product/business, applies to either
Kensa Integration Gaps	Unchanged — applies to Go integration too (K-4..K-12)
Go Rebuild — Deferred Features	PATCH credentials, bulk hosts import, SSH-key vault, SSE follow-ups, Specter workaround
CI / Flakes	Three p99 latency flakes hit this session (TestEmitSync_Latency, TestEnqueue_LatencyP99, TestVerify_P99Latency) — consider widening budgets or moving to a perf suite

Companion docs (local-only, gitignored)

• CLAUDE.md — added a STATUS banner at the top naming app/ as the active tree and backend/ + root frontend/ as FROZEN. Updated the Domain-Specific Guides, Quick Reference table, and Quality Sweep Commands to point at the Go tree.
• docs/handoff/2026-06-04-session-handoff.md — end-of-session handoff for the next operator/model. Includes the docs/ audit recommendations (archive/update/keep) that I did not unilaterally execute.

Test plan

• grep -niE "python|fastapi|backend/app|backend/CLAUDE|mypy|flake8|pytest|requirements\.txt" BACKLOG.md returns only the two intentional "FROZEN tree" + priority-legend mentions.
• All Go Rebuild items + today's completed PRs accounted for.
• No PR/spec links broken (no spec changes; PR numbers verified against git log).