ci: Notify linked issues on release

[markushi]

Summary

• Add a release workflow that comments on GitHub issues closed by PRs included in a published stable release
• Document that PR authors need to use GitHub closing keywords (Fixes #123, etc.) for linked issues to receive the release notification

Mirrors getsentry/sentry-dart#3685

Test plan

• Review workflow against this repo's release and changelog conventions
• Monitor the first stable release run to confirm the action comments on issues linked through closing keywords

#skip-changelog
🤖 Generated with Claude Code

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.40.0 (1)	release

⚙️ sentry-android Build Distribution Settings

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	355.61 ms	360.69 ms	5.08 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
2195398	319.02 ms	342.38 ms	23.36 ms
d364ace	411.72 ms	430.81 ms	19.10 ms
d15471f	286.65 ms	314.68 ms	28.03 ms
ff8eea4	313.42 ms	337.08 ms	23.66 ms
17a0955	372.53 ms	446.70 ms	74.17 ms
23d6b12	354.10 ms	408.38 ms	54.28 ms
cf708bd	408.35 ms	458.98 ms	50.63 ms
6edfca2	305.52 ms	432.78 ms	127.26 ms
72020f8	312.32 ms	370.94 ms	58.62 ms
6b019b7	343.31 ms	417.23 ms	73.91 ms

App size

Revision	Plain	With Sentry	Diff
2195398	0 B	0 B	0 B
d364ace	1.58 MiB	2.11 MiB	539.75 KiB
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
ff8eea4	1.58 MiB	2.28 MiB	718.64 KiB
17a0955	1.58 MiB	2.10 MiB	533.20 KiB
23d6b12	1.58 MiB	2.10 MiB	532.31 KiB
cf708bd	1.58 MiB	2.11 MiB	539.71 KiB
6edfca2	1.58 MiB	2.13 MiB	559.07 KiB
72020f8	1.58 MiB	2.19 MiB	620.21 KiB
6b019b7	0 B	0 B	0 B

[romtsn]

awesome! I wanted to add this for so long, thanks