feat: add /catch-up and /debug guided commands to draft welcome

Replace the 'What changed recently' draft chip with /catch-up, a command
whose hidden prompt branches on git state: reconstruct intent from an
in-progress diff, check an open PR's review state, or summarize recent
commits.

Add /debug as a new draft chip and command: a guided root-cause
investigation that captures the symptom, forms hypotheses, checks them
against the code, and confirms the cause before proposing a fix.

Both follow the /workspace-review pattern — visible + hidden magic
prompts wired into command autocomplete, the submit handler, draft preset
chips, and the Magic Prompts settings page, with i18n across all locales.

packages/ui/src/components/sections/magic-prompts/MagicPromptsPage.tsx

@@ -148,6 +148,22 @@ const PROMPT_PAGE_MAP: Record<string, PromptPageConfig> = {
       { id: 'session.plan.instructions', titleKey: 'settings.magicPrompts.page.block.instructions' },
     ],
   },
+  'session.catchup': {
+    titleKey: 'settings.magicPrompts.page.group.sessionCatchUp.title',
+    descriptionKey: 'settings.magicPrompts.page.group.sessionCatchUp.description',
+    blocks: [
+      { id: 'session.catchup.visible', titleKey: 'settings.magicPrompts.page.block.visiblePrompt' },
+      { id: 'session.catchup.instructions', titleKey: 'settings.magicPrompts.page.block.instructions' },
+    ],
+  },
+  'session.debug': {
+    titleKey: 'settings.magicPrompts.page.group.sessionDebug.title',
+    descriptionKey: 'settings.magicPrompts.page.group.sessionDebug.description',
+    blocks: [
+      { id: 'session.debug.visible', titleKey: 'settings.magicPrompts.page.block.visiblePrompt' },
+      { id: 'session.debug.instructions', titleKey: 'settings.magicPrompts.page.block.instructions' },
+    ],
+  },
   'session.fusion': {
     titleKey: 'settings.magicPrompts.page.group.sessionFusion.title',
     descriptionKey: 'settings.magicPrompts.page.group.sessionFusion.description',

packages/ui/src/components/sections/magic-prompts/MagicPromptsSidebar.tsx

@@ -48,6 +48,8 @@ export const MagicPromptsSidebar: React.FC<MagicPromptsSidebarProps> = ({ onItem
           { id: 'session.summary', titleKey: 'settings.magicPrompts.sidebar.item.sessionSummary' },
           { id: 'session.review', titleKey: 'settings.magicPrompts.sidebar.item.sessionWorkspaceReview' },
           { id: 'session.plan', titleKey: 'settings.magicPrompts.sidebar.item.sessionFeaturePlan' },
+          { id: 'session.catchup', titleKey: 'settings.magicPrompts.sidebar.item.sessionCatchUp' },
+          { id: 'session.debug', titleKey: 'settings.magicPrompts.sidebar.item.sessionDebug' },
           { id: 'session.fusion', titleKey: 'settings.magicPrompts.sidebar.item.sessionFusion' },
         ],
       },