[codex] Harden dashboard run activity charts (#4126)

## Thinking Path

> - Paperclip gives operators a live view of agent work across
dashboards, transcripts, and run activity charts
> - Those views consume live run updates and aggregate run activity from
backend dashboard data
> - Missing or partial run data could make charts brittle, and live
transcript updates were heavier than needed
> - Operators need dashboard data to stay stable even when recent run
payloads are incomplete
> - This pull request hardens dashboard run aggregation, guards chart
rendering, and lightens live run update handling
> - The benefit is a more reliable dashboard during active agent
execution

## What Changed

- Added dashboard run activity types and backend aggregation coverage.
- Guarded activity chart rendering when run data is missing or partial.
- Reduced live transcript update churn in active agent and run chat
surfaces.
- Fixed issue chat avatar alignment in the thread renderer.
- Added focused dashboard, activity chart, and live transcript tests.

## Verification

- `pnpm install --frozen-lockfile --ignore-scripts`
- `pnpm exec vitest run server/src/__tests__/dashboard-service.test.ts
ui/src/components/ActivityCharts.test.tsx
ui/src/components/transcript/useLiveRunTranscripts.test.tsx`
- Result: 8 tests passed, 1 skipped. The embedded Postgres dashboard
service test skipped on this host with the existing PGlite/Postgres init
warning; UI chart and transcript tests passed.

## Risks

- Medium-low risk: aggregation semantics changed, but the UI remains
guarded around incomplete data.
- The dashboard service test is host-skipped here, so CI should confirm
the embedded database path.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex coding agent based on GPT-5, tool-enabled local shell and
GitHub workflow, exact runtime context window not exposed in this
session.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots, or documented why targeted component tests are sufficient
here
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/components/IssueChatThread.tsx

@@ -1060,7 +1060,7 @@ function IssueChatUserMessage({ message }: { message: ThreadMessage }) {
     userProfileMap,
   });
   const authorAvatar = (
-    <Avatar size="sm" className="mt-1 shrink-0">
+    <Avatar size="sm" className="shrink-0">
       {avatarUrl ? <AvatarImage src={avatarUrl} alt={resolvedAuthorName} /> : null}
       <AvatarFallback>{initialsForName(resolvedAuthorName)}</AvatarFallback>
     </Avatar>
@@ -1248,7 +1248,7 @@ function IssueChatAssistantMessage({ message }: { message: ThreadMessage }) {
   return (
     <div id={anchorId}>
       <div className="flex items-start gap-2.5 py-1.5">
-        <Avatar size="sm" className="mt-0.5 shrink-0">
+        <Avatar size="sm" className="shrink-0">
           {agentIcon ? (
             <AvatarFallback><AgentIcon icon={agentIcon} className="h-3.5 w-3.5" /></AvatarFallback>
           ) : (