fix: Fix UITouch background thread access in SentryTouchTracker

[philprime]

📜 Description

This PR fixes a crash caused by accessing UITouch instances from a background thread in . The fix extracts all necessary data from UITouch objects on the main thread before dispatching to the background queue, then processes only thread-safe data structures on the background thread.

Changes:

• Added ExtractedTouchData struct to hold thread-safe touch information
• Changed trackedTouches dictionary to use ObjectIdentifier as key instead of UITouch
• Extract touch.location, touch.phase, and ObjectIdentifier on calling thread (main thread)
• Process only thread-safe data structures (structs, enums, value types) on background queue

💡 Motivation and Context

Fixes #6231

The issue was that trackTouchFrom(event:) dispatched to a background queue and then accessed UITouch properties (touch.location(in: nil) and touch.phase) from that background thread. This violates UIKit's thread-safety requirements and caused EXC_BAD_ACCESS crashes.

The stack trace from the issue showed:

EXC_BAD_ACCESS: Attempted to dereference garbage pointer 0x400000000000bad0.
...
2  REDACTED +0xcbebc0                closure #1 in SentryTouchTracker.trackTouchFrom(event:)
...
5  libdispatch.dylib +0x1ad8       __dispatch_call_block_and_release

💚 How did you test it?

• All 12 existing tests in SentryTouchTrackerTests pass successfully
• Verified no UIKit objects cross the thread boundary by code review
• All UITouch accesses now happen on the calling thread before dispatching

📝 Checklist

• I added tests to verify the changes. (Existing tests verify behavior remains unchanged)
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed. (No doc changes needed - internal fix)
• I updated the wizard if needed. (No wizard changes needed)
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.097%. Comparing base (5fce94f) to head (e6a3249).
⚠️ Report is 1 commits behind head on v8.x.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@              Coverage Diff              @@
##              v8.x     #6584       +/-   ##
=============================================
+ Coverage   85.196%   86.097%   +0.901%     
=============================================
  Files          441       441               
  Lines        27426     27470       +44     
  Branches     10368     11933     +1565     
=============================================
+ Hits         23366     23651      +285     
+ Misses        4018      3773      -245     
- Partials        42        46        +4     

Files with missing lines	Coverage Δ
...ntegrations/SessionReplay/SentryTouchTracker.swift	100.000% <100.000%> (ø)

... and 33 files with indirect coverage changes

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1222.43 ms	1246.13 ms	23.69 ms
Size	23.75 KiB	992.25 KiB	968.50 KiB

Baseline results on branch: v8.x

Startup times

Revision	Plain	With Sentry	Diff
ab82dac	1213.12 ms	1240.92 ms	27.80 ms
c11a8e0	1203.00 ms	1223.23 ms	20.23 ms
ab82dac	1249.73 ms	1272.69 ms	22.96 ms
41834f1	1235.15 ms	1256.31 ms	21.17 ms
f76f6bf	1207.70 ms	1233.27 ms	25.57 ms
b66be9b	1218.22 ms	1244.19 ms	25.96 ms
5fce94f	1226.31 ms	1246.82 ms	20.50 ms
a7a0a2b	1218.61 ms	1248.69 ms	30.08 ms
e537c90	1226.22 ms	1256.64 ms	30.41 ms
3af1ae9	1225.60 ms	1252.65 ms	27.05 ms

App size

Revision	Plain	With Sentry	Diff
ab82dac	23.75 KiB	991.86 KiB	968.11 KiB
c11a8e0	23.75 KiB	991.86 KiB	968.12 KiB
ab82dac	23.75 KiB	991.85 KiB	968.10 KiB
41834f1	23.75 KiB	991.88 KiB	968.13 KiB
f76f6bf	23.74 KiB	981.30 KiB	957.56 KiB
b66be9b	23.75 KiB	996.03 KiB	972.28 KiB
5fce94f	23.75 KiB	991.62 KiB	967.87 KiB
a7a0a2b	23.75 KiB	996.04 KiB	972.29 KiB
e537c90	23.75 KiB	992.03 KiB	968.28 KiB
3af1ae9	23.74 KiB	981.29 KiB	957.55 KiB

Previous results on branch: philprime/removeuitouch-backgruond

Startup times

Revision	Plain	With Sentry	Diff
1568203	1212.58 ms	1241.50 ms	28.92 ms

App size

Revision	Plain	With Sentry	Diff
1568203	23.75 KiB	989.86 KiB	966.11 KiB

[itaybre]

lgtm

[itaybre]

CI is being very slow, I am backporting some fixes on #6604 to help this PR and the later release