chore: Add Dependabot (#5380)

* chore(deps): Add Dependabot for Gradle plugins

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore(deps): Exclude Spring Boot from Dependabot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore(deps): Add commit message prefix for Dependabot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore(deps): Set dependabot to weekly and add dependency grouping

Switch both gradle and github-actions ecosystems from daily to weekly.
Group related dependencies so they're updated together in single PRs
(androidx, compose, kotlin, spring, opentelemetry, graphql, jackson,
and all github-actions).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fixup: Remove gradle dependency groups, keep only gh-actions group

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore(deps): Add gradle dependency groups for androidx, compose, kotlin, jackson

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore(deps): Set dependabot to daily and reorder compose group

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>