chore: release core 2.0.0 and plugins with segment_analytics 2.x support

[MichaelGHSeg]

Summary

Release PR for segment_analytics 2.0.0 and patch releases of all six plugins so they resolve against it. First release through the tag-push publish workflow (#223).

Core: 1.1.13 → 2.0.0

Major bump because the minimum Flutter version rises to 3.38 (#220). Pub resolves the SDK constraint for the whole package, so this is breaking on every platform, not just iOS. The Dart API is unchanged.

• Breaking: Flutter ≥ 3.38 (feat: add iOS UIScene life cycle support #220)
• iOS UIScene life cycle support for deep links (feat: add iOS UIScene life cycle support #220)
• iOS User-Agent generated like analytics-swift, not read from WKWebView. This removes a launch-time main-thread stall, and the value changes: real OS version, and CPU iPad OS on iPad (fix(ios): align user agent with analytics-swift #222)
• Web: persistence fixed under --wasm builds (Fix conditional import after migration to package:web  #165)

pubspec.yaml, lib/version.dart, CHANGELOG.md (the unreleased 1.2.0 section from #220 becomes 2.0.0) and the README compatibility note are updated.

Plugins

Every plugin pinned core at ^1.x, so none would resolve with 2.0.0. Each constraint is widened to <3.0.0 with its existing floor kept, so the plugins keep working for apps that stay on core 1.x.

Plugin	Version	Notes
adjust	1.0.2 → 1.0.3
advertising_id	1.0.0 → 1.0.1	also ships #77 (Android "Reply already submitted" crash with Limit Ad Tracking on), merged in 2024 but never published
amplitude	1.0.0 → 1.0.1
appsflyer	1.0.2 → 1.0.3
firebase	1.0.1 → 1.0.2
idfa	1.0.3 → 1.0.4

Other changes since each plugin's last publish are README/CI only (#172, #210).

Testing (Flutter 3.38.0, locally)

• .github/scripts/check-release-metadata.sh passes for all seven tags below
• core: flutter analyze clean, 127/127 tests, dart pub publish --dry-run 0 warnings
• each plugin: dart pub publish --dry-run 0 warnings except amplitude's old library-name warning (lib/plugin_amplitude.dart vs the package name; not blocking, and renaming would break imports); with core overridden to this branch's 2.0.0, every plugin resolves segment_analytics 2.0.0 and flutter analyze is clean

After merge

Tag the merge commit on main and push, core first:

segment_analytics-v2.0.0

Approve the publish job, wait for 2.0.0 on pub.dev, then:

segment_analytics_plugin_adjust-v1.0.3
segment_analytics_plugin_advertising_id-v1.0.1
segment_analytics_plugin_amplitude-v1.0.1
segment_analytics_plugin_appsflyer-v1.0.3
segment_analytics_plugin_firebase-v1.0.2
segment_analytics_plugin_idfa-v1.0.4

The plugins don't strictly need core 2.0.0 on pub.dev (their floor is 1.x), but publishing core first means a failed first CI publish can be fixed before tagging six more.