perf: Implement O(1) Lookup Map for internalId

Input from Gemini 3 Pro:

✦ Architecture & Implementation Plan (Handoff)

Objective: Restore O(1) performance for internalId lookups. Currently, the framework relies on store.items.find(...) in critical paths (selection, navigation), which is O(N) and creates performance bottlenecks for large datasets.

Architectural Decision: We will implement Option A: Direct Reference Map. internalIdMap will map internalId -> Item Reference (either a Record instance or a Raw Data Object).

Implementation Plan:

1. Enhance Neo.collection.Base:

   • Add trackInternalId: false (config).
   • Add internalIdMap: null (property, initialized if tracking is enabled).
   • Add getInternalKey(item) method (hook, default returns null).
   • Update splice and afterSetItems logic to:
     • Get the internal key via getInternalKey(item).
     • If valid, add to internalIdMap.
     • On remove, delete from internalIdMap.
   • Add getByInternalId(id) accessor method.

2. Update Neo.data.Store:

   • Set trackInternalId: true by default.
   • Override getInternalKey(item) to return item[internalId] (using the symbol).
   • Turbo Mode Sync: In get(key) and getAt(index), when a Raw Object is hydrated into a Record:
     • Explicitly update internalIdMap to point to the new Record instance instead of the old Raw Object.
     • This ensures getByInternalId returns the correct reference used by the View.

3. Refactor Consumers (Cleanup Phase):

   • Update Helix, Gallery, ComboBox, GridBody, TableBody, and SelectionModels.
   • Replace all instances of store.items.find(r => ... === id) with store.getByInternalId(id).
   • This will dramatically simplify the record resolution logic and restore performance.

Note: The internalId symbol is exported from src/core/ConfigSymbols.mjs. Use it to access the property safely.

Input from Gemini 3 Pro:

✦ I have implemented the O(1) internalIdMap lookup.

Summary of Changes:

1. Core Framework (Neo.collection.Base & Neo.data.Store):

   • Implemented internalIdMap (Map) in Collection to track items by internalId.
   • Added trackInternalId config (defaults to false in Collection, true in Store).
   • Updated splice, filter, clear, and destroy to maintain the map.
   • Enhanced get(key) to automatically check internalIdMap if the key is not found in the primary map.
   • Updated Store to populate internalIdMap with Record instances upon hydration.

2. Consumer Refactoring:

   • Refactored GridBody, TableBody, List, Gallery, Helix, and DragZone to use the optimized store.get() method.
   • Removed all O(N) fallback iterations (e.g., store.items.find(...)) in Selection Models and Components.

3. Verification:

   • Created a new unit test: test/playwright/unit/collection/InternalId.spec.mjs.
   • Verified trackInternalId toggling, map population, record resolution, and cleanup on filter/splice/destroy.
   • All 8 tests passed.

The system now has O(1) performance for both Primary Key and Internal ID lookups.