Configure Spotless through convention plugins

[gpunto]

Goal

AND-880

As the title says.

Note: I'm not running spotlessApply here to avoid bundling the migration with all the Spotless changes. I'll do it in a follow up (#143). What will change:

• The headers will add an empty line -> This is how chat & video were configured, so I used their template to minimize the overall changes, since core & feeds' codebases are smaller
• XML files now get the license header too

Implementation

Replace local Spotless configuration with the convention.

Testing

Run spotlessApply and verify that the files are updated accordingly.

Checklist

• Issue linked (if any)
• Tests/docs updated
• I have signed the Stream CLA (required for external contributors)

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled.

🎉 Great job! This PR is ready for review.

[Copilot]

Pull Request Overview

This PR migrates from a manual Spotless plugin configuration to using a centralized convention plugin (streamConventions 0.3.0). The changes eliminate custom license management tasks and delegate formatting responsibilities to the convention plugin.

• Removes direct Spotless plugin dependency in favor of stream-project convention plugin
• Updates streamConventions version from 0.1.1 to 0.3.0
• Deletes license template files and custom license generation tasks

Reviewed Changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated no comments.

File	Description
gradle/libs.versions.toml	Updates streamConventions version to 0.3.0, removes spotless plugin reference, and adds stream-project plugin
build.gradle.kts	Replaces manual spotless configuration with streamProject DSL, removes custom license generation tasks and unused imports
config/license/license.template	Removes license template file (now handled by convention plugin)
config/license/generated/license-2025.txt	Removes generated license file (now handled by convention plugin)

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[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-feeds-android-client	2.36 MB	2.36 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
91.9% Coverage on New Code
0.7% Duplication on New Code

See analysis details on SonarQube Cloud