fix: emit type='related_activity_log' from RelatedActivityLogSource

[AsmitNepali]

Summary

Closes #11.

RelatedActivityLogSource::makeEntry() previously emitted type='activity_log' — same as ActivityLogSource — so ->ofType(['related_activity_log']) silently matched nothing despite source_priorities.related_activity_log being a real config key. The two axes (entry-type vs priority-key) now agree.

Changes

• src/Timeline/Sources/RelatedActivityLogSource.php — emit type='related_activity_log'.
• src/ActivityLogServiceProvider.php — also auto-register ActivityLogRenderer for the related_activity_log type so spatie-diff rendering still works for related-log entries out of the box.
• tests/Feature/BuilderDedupTest.php — assertion updated to reflect the new winning type when fromActivityLogOf wins dedup.
• Docs: removed the now-obsolete troubleshooting entry; refreshed the type-taxonomy table in how-it-works.md; updated sources.md, refining-the-timeline.md, filament-ui.md, configuration.md to document four entry types instead of three.

BC note

Filters using ->ofType(['activity_log']) no longer pick up entries from RelatedActivityLogSource. To match both spatie-log sources, pass both keys:

->ofType(['activity_log', 'related_activity_log'])

To distinguish own-log vs related-log at the entry level, $entry->relatedModel is still the right discriminator (null vs Eloquent model).

Test plan

• vendor/bin/pest — 44 passed
• Manual verify ->ofType(['related_activity_log']) returns related-log entries on a real subject
• Confirm built-in renderer still picks up related-log entries in Filament UI