…and drill-down browse

- Stop dumping the full ~1,500-item catalog (blocks, tools, triggers, 1,000+ tool operations, docs) into the palette on open; surface them only once the user types, mirroring the existing integrations group
- Add a curated empty state: frecency-ranked Recents (new persisted store) and a Browse section that drills into block/trigger/integration categories
- Scope drill-down shown as a removable pill in the search bar; Backspace on empty input or Escape pops the scope
- Cap each result group to keep the DOM bounded on broad queries
- Derive browse categories from block category + integrationType

- Fix stale input text when entering/exiting a browse scope: the cmdk
  Command.Input is uncontrolled, so resetting requires the native value
  setter, not just setSearch(''). Extract the existing open-reset logic into
  a shared clearInput() and reuse it for open, enter-scope, and exit-scope
- Short-circuit the recents memo when there are no recorded entries
- Use a distinct icon for the Productivity category (was reusing Core Blocks')
- Add unit coverage for the recents store and frecency scoring

…etically

- Lead with workflow primitives (Core Blocks, Triggers), then pin AI first
  (Sim is an AI workspace) and rank remaining integration categories by
  breadth (most integrations first) so the richest categories surface first
- Personal frequency is already covered by Recents, so the static order
  optimizes for discovery and self-maintains as integrations are added
- Reuses the canonical integration taxonomy (INTEGRATION_TYPE_LABELS) shared
  with the /integrations page rather than inventing a parallel one

…tive

Review-loop findings:
- Recents were pruned by raw recency but ranked by frecency, so a frequently
  used older block could be evicted while still ranking high. Prune by the same
  frecencyScore used for display; add a regression test
- Make the integration category icon map exhaustive over IntegrationType so a
  newly added category is a compile error instead of a silent generic-icon
  fallback; drive core-block/trigger icons off the category kind
- Factor the shared gate-and-cap rule for the catalog search groups into a
  single cappedCatalog() helper instead of repeating it across five memos

…the palette

Workflows/files/chats/tables/KBs were rendered in full at the empty state, so a
workspace with thousands of them dumped thousands of rows into the DOM. Factor
the catalog cap into a shared filterAndCap() and apply it to all variable-size
groups, bounding palette DOM to MAX_RESULTS_PER_GROUP per group regardless of
workspace size.

…es them

The directory imports resolve to the search-groups and command-items barrels;
BrowseGroup, RecentsGroup, RecentRenderItem, and MemoizedCategoryItem were
added to the source files but not re-exported, breaking the Turbopack build
(tsc resolved them via the source file and missed it).

…cideIcon

The map mixes lucide and emcn icons (Database comes from @/components/emcn/icons,
which is not a LucideIcon). Type it as ComponentType<{ className?: string }> —
the exact type MemoizedCategoryItem's icon prop consumes — which both icon
sources satisfy, keeping the exhaustive IntegrationType key check.