chore: remove stale Carthage and semantic-release artifacts

[nickolas-dimitrakas]

Summary

• Carthage is no longer a supported distribution method (no Cartfile, no CI job for Carthage consumers)
• semantic-release is no longer used

Changes

Deleted:

• Scripts/carthage.sh — Carthage build wrapper
• Scripts/release.sh — called only by semantic-release
• release.config.js — semantic-release config
• mParticle_Apple_SDK.json — Carthage binary manifest (version-to-URL map)

Updated:

• README.md — removed Carthage installation section and Carthage column from kits table
• AGENTS.md — updated distribution methods to SPM + CocoaPods only, removed stale script references
• SwiftExample/README.md — removed chmod +x ./Scripts/carthage.sh line
• .github/workflows/sdk-release-maintenance-branch.yml — removed "Update Carthage JSON manifest" step, carthage.sh chmod, and mParticle_Apple_SDK.json from git add/commit message

Test plan

• trunk check passes (verified locally — no issues)
• Release workflow still builds and uploads xcframeworks to S3 correctly
• No remaining Carthage references in docs/CI (CHANGELOG.md historical entries are intentionally kept)

🤖 Generated with Claude Code

[cursor]

PR Summary

Medium Risk
Medium risk because it modifies the release automation workflow and deletes release-related scripts/manifests, which could break future release runs if any hidden dependencies remain. Product/runtime SDK code is untouched, so risk is largely limited to packaging and documentation.

Overview
Drops Carthage and semantic-release support artifacts by deleting Scripts/carthage.sh, Scripts/release.sh, release.config.js, and the Carthage binary manifest mParticle_Apple_SDK.json.

Updates release automation and docs to remove Carthage-specific steps and references: the maintenance-branch release workflow no longer updates/commits the JSON manifest or chmod the Carthage wrapper, and README.md, AGENTS.md, and SwiftExample/README.md now describe distribution via Swift Package Manager and CocoaPods only.

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[github-actions]

📦 SDK Size Impact Report

Measures how much the SDK adds to an app's size (with-SDK minus without-SDK).

Metric	Target Branch	This PR	Change
App Bundle Impact	1.75 MB	1.75 MB	+N/A
Executable Impact	848 bytes	848 bytes	+N/A
XCFramework Size	6.38 MB	6.38 MB	+N/A

➡️ SDK size impact change is minimal.

Raw measurements

Target branch (main):

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1880,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":1796,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6532}

This PR:

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1880,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":1796,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6532}