feat(quart): Add span streaming support to Quart integration

[ericapisani]

Add span streaming support for the Quart integration when the
trace_lifecycle stream experiment is enabled. Sets HTTP request
attributes (method, headers, URL, query, client IP) on the segment
span and uses the correct source constant from sentry_sdk.traces
for span-first mode.

Depends on #6501
being merged first.

Fixes PY-2352
Fixes #6050

[linear-code]

PY-2352

[github-actions]

Codecov Results 📊

✅ 88506 passed | ⏭️ 6022 skipped | Total: 94528 | Pass Rate: 93.63% | Execution Time: 297m 57s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +80
Passed Tests	📈 +80
Failed Tests	—
Skipped Tests	—

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2474 uncovered lines.
✅ Project coverage is 89.38%. Comparing base (base) to head (head).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/integrations/quart.py	100.00%	⚠️ 3 partials

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
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+ Coverage    89.37%    89.38%    +0.01%
==========================================
  Files          192       192         —
  Lines        23285     23306       +21
  Branches      8002      8016       +14
==========================================
+ Hits         20811     20832       +21
- Misses        2474      2474         —
- Partials      1309      1312        +3

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[sentrivana]

We'll need a streaming counterpart for this piece of code, something like:

client = sentry_sdk.get_client()

if has_span_streaming_enabled(client.options):
    span = get_current_span()
    if span is not None:
        span._segment._update_active_thread()

[sentrivana]

We should also set user.id if we have it (essentially port _add_user_to_event).

It's one of the attributes that should be set on all spans, not just the segment, so it should be set on the scope.

Maybe extract the code that fetches the user id from _add_user_to_event to a helper func, get rid of _add_user_to_event and set the user id in the event processor directly, and in the streaming path set it on the current scope?

def _fetch_user_id() -> None:
    if quart_auth is None:
        return

    user = quart_auth.current_user
    if user is None:
        return

    try:
        return quart_auth.current_user._auth_id
    except Exception:
        return None

and then here

user_id = _fetch_user_id()
if user_id is not None:
    sentry_sdk.get_current_scope().set_attribute("user.id", user_id)

and in the event processor

user_id = _fetch_user_id()
if user_id is not None:
    user_info = event.setdefault("user", {})
    user_info["id"] = user_id

[sentrivana]

Please also add a test for this if there is none.