fix: make /catch-up branch-aware and layered, with product-focused next step

Rework the /catch-up decision tree from mutually-exclusive cases into
complementary layers. It now determines whether the current branch is the
repo's default branch and builds context accordingly: on a feature branch
it reads enough of the branch's own commits to grasp the intent and checks
the branch's PR even when there are uncommitted changes (so in-progress
work is understood as part of the larger effort); on the default branch it
lightly skims recent commits. Uncommitted changes remain the focal point
but are interpreted through that context.

The suggested next step now favors continuing the actual work over
housekeeping — since running catch-up implies the user stepped away and
the work is likely unfinished, push/PR/checks are only a fallback. Updates
the Magic Prompts settings descriptions across locales to match.

packages/ui/src/lib/i18n/messages/en.settings.ts

@@ -1696,7 +1696,7 @@ export const settingsDict = {
   'settings.magicPrompts.page.group.sessionFeaturePlan.title': 'Feature Planning',
   'settings.magicPrompts.page.group.sessionFeaturePlan.description': 'Prompts used by the /plan-feature slash command: visible user message + hidden instructions. Runs a guided dialogue that researches the code and asks clarifying questions in small batches before producing an implementation plan.',
   'settings.magicPrompts.page.group.sessionCatchUp.title': 'Catch Up',
-  'settings.magicPrompts.page.group.sessionCatchUp.description': 'Prompts used by the /catch-up slash command: visible user message + hidden instructions. Inspects git state and branches on it — reconstructs intent from an in-progress diff, checks an open PR\'s review state, or summarizes recent commits.',
+  'settings.magicPrompts.page.group.sessionCatchUp.description': 'Prompts used by the /catch-up slash command: visible user message + hidden instructions. Builds branch-aware context — the branch\'s commits, its PR, and uncommitted work together — to understand what you were doing, then gives a warm orientation and a product-focused next step.',
   'settings.magicPrompts.page.group.sessionDebug.title': 'Debugging',
   'settings.magicPrompts.page.group.sessionDebug.description': 'Prompts used by the /debug slash command: visible user message + hidden instructions. Runs a guided root-cause investigation — captures the symptom, forms hypotheses, checks them against the code, and confirms the cause before proposing a fix.',
   'settings.magicPrompts.page.group.sessionWeigh.title': 'Weigh Options',