Sub-issue: Add support for triggering pipelines on Git tags

[pepedinho]

Context / Problem
Currently, Fleet only supports triggering pipelines on branch updates. This works for most continuous integration flows, but it’s limiting when workflows rely on versioned releases or tag-based deployments.

Goal
Extend the existing push trigger to also react to Git tag updates (e.g. v1.0.0, release-*).
This should allow users to define tags alongside branches in the triggers configuration of fleet.yml.

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Proposed Changes

• Update trigger parsing logic to support a tags field in addition to branches.
• Detect and handle new or updated tags in the remote repository.
• Ensure tags can be filtered using glob patterns (e.g. v* or release-*).
• Make the trigger behave consistently with branch triggers (e.g., same logging and pipeline execution flow).

Example

triggers:
  push:
    branches: [main, develop]
    tags: [v*, release-*]

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Acceptance Criteria

• Pipelines can be triggered by a push on a matching tag.
• Tag filtering works with exact matches and glob patterns.
• Trigger origin (branch vs tag) is clearly displayed in pipeline logs.
• Backward compatibility is preserved for branch-only configurations.

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Notes / Risks

• Ensure tag detection does not conflict with branch triggers (e.g., when a tag and a branch share the same name).
• Properly handle annotated and lightweight tags.
• Confirm behavior on tag deletion or re-tagging scenarios.