When filtering child summaries to include in parent summary,
use valid? instead of any_resources?. This ensures custom type
summaries (which have 0 resources by design) are included.

Without this fix, custom type summaries were created and validated
but never included in the parent summary's items.

Adds integration test that verifies custom type summaries are
included in parent summary output even when they have no resources,
while regular summaries without resources are correctly excluded.

Also updates lefthook to run full test suite on pre-push to catch
integration issues that may not be detected by only running tests
for changed files.

Clarify the intent of validation methods in SummaryBuilder and IssueBuilder:
- should_create_issue?: Determines if a summary/issue should be posted
  as a GitLab issue (requires title AND content). Returns boolean.
- has_content?: Determines if a summary should be included in a parent
  summary (custom summaries always have content, regular summaries need
  resources). Returns boolean.

This makes the code more explicit and easier to understand. The logic
for custom vs regular summaries is now consolidated in one place
instead of being duplicated with ternary operators.

Updated all usages and tests to use the new method names.

- Changed filtering logic to use content_available? method
- Renamed methods for clarity:
  - kept valid? (describes object state, Ruby idiom)
  - added content_available? (checks if summary has content for parent)
  - added title_present? helper (returns explicit boolean)
- Fixed !! pattern - use ternary for explicit boolean conversion
- Custom type summaries generate content from templates, regular summaries
  need resources
- Updated all usages and tests

The any_resources? method was only used once in content_available?.
Inlined it to simplify the code and removed corresponding tests.

The variable was confusing because it's not GitLab issues,
but an array of SummaryBuilder instances (child summaries).

Use 'expect(subject).to be_valid' instead of 'expect(subject.valid?).to be(true)'
for better readability and idiomatic RSpec style.

Fix: Include custom type summaries in parent summary

See merge request !366



Merged-by: Kev Kloss <kkloss@gitlab.com>
Approved-by: Kev Kloss <kkloss@gitlab.com>
Reviewed-by: Kev Kloss <kkloss@gitlab.com>
Co-authored-by: ddieulivol <ddieulivol@gitlab.com>

Release v1.48.0

See merge request !367



Merged-by: David Dieulivol <ddieulivol@gitlab.com>
Approved-by: Ievgen Chernikov <ichernikov@gitlab.com>