refactor(samples): Convert main screen to Jetpack Compose

[markushi]

📜 Description

Converts the MainActivity from Java to Kotlin, categorizing all our buttons a bit nicer too.

requires #5016 to be merged first.

💡 Motivation and Context

Modernizes the sample app to use Kotlin, which is now the recommended language for Android development. This makes the sample more representative of current best practices and simplifies future enhancements.

💚 How did you test it?

Manual testing of the sample app to ensure functionality remains unchanged.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if 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.

🔮 Next steps

#skip-changelog

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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[sentry]

Bug: The file copy loop incorrectly writes the entire buffer instead of the number of bytes read, potentially corrupting the output file with garbage data from previous reads.
_{Severity: MEDIUM}

Suggested Fix

Capture the number of bytes returned by inputStream.read(bytes) into a length variable. Then, call outputStream.write(bytes, 0, length) to ensure only the valid bytes that were just read are written to the output stream.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location:
sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/MainActivity.kt#L153

Potential issue: The file copy logic reads from an `inputStream` into a `bytes` buffer
but does not use the return value of `inputStream.read(bytes)`, which indicates the
actual number of bytes read. Instead, it calls `outputStream.write(bytes)`, which writes
the entire buffer. On the final read, if the remaining data is smaller than the buffer
size, the buffer will contain valid data followed by stale data from the previous
iteration. Writing the full buffer appends this garbage data to the output file,
resulting in a corrupted file attachment for every Sentry event.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	350.63 ms	394.56 ms	43.93 ms
Size	1.58 MiB	2.19 MiB	620.05 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
dba088c	333.98 ms	381.16 ms	47.18 ms
91bb874	310.68 ms	359.24 ms	48.56 ms
d15471f	315.61 ms	360.22 ms	44.61 ms
27d7cf8	314.17 ms	347.00 ms	32.83 ms
a5ab36f	316.83 ms	394.54 ms	77.71 ms
5b66efd	308.67 ms	363.85 ms	55.18 ms
abfcc92	337.38 ms	427.39 ms	90.00 ms
fc5ccaf	279.11 ms	353.34 ms	74.23 ms
fcec2f2	328.91 ms	387.75 ms	58.84 ms
dba088c	365.46 ms	366.31 ms	0.85 ms

App size

Revision	Plain	With Sentry	Diff
dba088c	1.58 MiB	2.13 MiB	558.99 KiB
91bb874	1.58 MiB	2.13 MiB	559.07 KiB
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
27d7cf8	1.58 MiB	2.12 MiB	549.42 KiB
a5ab36f	1.58 MiB	2.12 MiB	555.26 KiB
5b66efd	1.58 MiB	2.13 MiB	559.07 KiB
abfcc92	1.58 MiB	2.13 MiB	557.31 KiB
fc5ccaf	1.58 MiB	2.13 MiB	557.54 KiB
fcec2f2	1.58 MiB	2.12 MiB	551.50 KiB
dba088c	1.58 MiB	2.13 MiB	558.99 KiB