v6.2.0 — remove the live session dashboard

The live session dashboard is removed. It rendered, but it could not show what a
session was doing. The event log it read carries five fixed fields and no free
text, so there was nothing to label a node with, and a finished agent was erased
from the graph on SubagentStop — a completed session always ended as an empty
circle.

1. Removed. /harness-dashboard, hooks/dashboard/ (the SSE server, the
   node-graph page, the vendored animejs), hooks/dashboard-log.sh with its
   dashboard-log.py, and the VV_HARNESS_DASHBOARD opt-in. Anyone with that
   command or env var in a runbook will find it gone.

2. Six hooks stop firing. hooks/hooks.json routed PreToolUse,
   PostToolUse, SubagentStart, SubagentStop, PermissionRequest and
   PermissionDenied to dashboard-log.sh and nothing else. Only SessionStart
   and SessionEnd remain, so no session pays a hook per tool call for this.

3. The three quality gates lose their instrumentation. _dashboard_log()
   and every call site are gone from enforce-scope.sh, commit-gate.sh and
   verify-task-quality.sh, and from the three harness-init templates, which
   stay byte-identical. No verdict, exit code, stderr message or deny-JSON shape
   changed: the conformance suite's gates scores 1024/1024.

4. .harness/dashboard/ is neither created nor gitignored. Dropped from
   .gitignore, from doctor.py and fixes.py's REQUIRED_GITIGNORE_LINES,
   and from scripts/stamp.sh's idempotent appends. The canonical list is now
   .harness/SESSION_INCOMPLETE, .harness/features.json.lock,
   .harness/last_gate.json. An upgraded project keeps its stale ignore line
   until someone removes it by hand; nothing writes there any more.

5. Test and eval surface. test/run-tests.sh drops 1,858 lines of dashboard
   assertions; the hillclimb behavior and gates suites drop their dashboard-log
   checks. The F088–F116 feature records stay in .harness/features.json as
   history.