feat(issues): Render flamegraph attachments in issue details

[philprime]

Adds a dedicated Flamegraph section to issue details when an event has a version-1 event.flamegraph attachment. It uses the existing attachment listing and download endpoints, with loading, explicit retry, and unsupported-format handling. The section is gated by event-attachments and flamegraph-attachments.

The viewer reuses the profiling canvas, theme, hover tooltips, and scrolling used by MetricKit flamegraphs without changing the existing MetricKit implementation. A separate adapter converts attachment nodes into weighted paths, preserving inclusive counts, samples ending at intermediate nodes, repeated frames, and recursion. Multiple attachments and call trees can be selected independently. Unclassified frames use the system-frame color.

Backend prerequisite: #126459. Land the backend first so the feature flag is exposed to the UI.

The 33 focused tests include the existing MetricKit and view-hierarchy suites. Full frontend typechecking and lint passed. Playwright verification against a local event attachment confirmed a painted canvas, independent tree counts, hover tooltips, scrolling, and collapse persistence. Diagnostic payloads and browser artifacts are not included.

[github-actions]

Story previews

Preview the stories changed in this PR on the Vercel deployment:

• app/components/events/flamegraphAttachment/flamegraphAttachment.stories.mdx

_{Preview deployment: https://sentry-5iu4weiti.sentry.dev}

[github-actions]

📊 Type Coverage Diff

Metric	Before	After	Delta
Coverage	95.68%	95.68%	±0%
Typed	142,444	142,513	🟢 +69
Untyped	6,427	6,434	🔴 +7

🔍 7 new type safety issues introduced

any-typed symbols (3 new)

File	Line	Detail
static/app/components/events/flamegraphAttachment/utils.ts	60	frame (var)
static/app/components/events/flamegraphAttachment/utils.ts	85	tree (var)
static/app/components/events/flamegraphAttachment/utils.ts	120	child (var)

Non-null assertions (!) (2 new)

File	Line	Detail
static/app/components/events/flamegraphAttachment/index.tsx	34	data.trees[selectedTree]!
static/app/components/events/flamegraphAttachment/utils.ts	160	children[index]!

Type assertions (as) (2 new)

File	Line	Detail
static/app/components/events/flamegraphAttachment/utils.ts	139	as FlamegraphAttachmentData — payload as FlamegraphAttachmentData
static/app/components/events/flamegraphAttachment/utils.ts	148	as number[] — [] as number[]

This is informational only and does not block the PR.