feat(storybook): BaseNode V2 & LoopNode V2 — iterative design proposals

[1980computer]

Summary

• BaseNode V2 (BaseNodeV2.stories.tsx) — Anatomy page with shape docs, adornment slot diagram, Loop Count Badge reference table (what ↻ N means, when it appears, slot priority). Custom AdornmentResolverProvider keeps all V2 changes isolated from the original BaseNode story.
• LoopNode V2 (LoopNodeV2.stories.tsx) — New file. Full Anatomy page + two execution canvas stories.
• Storybook sort order — Anatomy surfaces first in both V2 sidebars.

LoopNode V2 — what's prototyped

Compound Iteration Picker

Replaces the original single ◄ / ► buttons with a richer compound control:

Control	Behaviour
|◄ / ►|	Jump to first / last iteration
◄ / ►	Step back / forward one iteration
[k / N]	Click the index number to type-jump to any iteration
All toggle	Collapses the picker into an aggregate view

Per-iteration status dots

A small coloured dot (●) appears next to the iteration number in the picker, reflecting that specific iteration's outcome — green (Completed), red (Failed), amber (In Progress), purple (Paused), grey (Cancelled).

Richer "All" aggregate

When the All toggle is active and status data is available, the badge shows ✓ completed ✗ failed with status colours instead of just Σ total.

Jump-to-failed shortcut

A ⚠ button appears whenever at least one iteration has a Failed status. One click jumps directly to the first failed iteration.

Iteration progress strip

A 1 px hairline at the bottom edge of the loop header fills proportionally as iterations reach a terminal state. Turns red if any iteration failed; green otherwise.

Execution Count documentation

Anatomy page includes a dedicated Execution Count subsection under V2 Iterations explaining:

• The denominator N in the picker = how many iterations the loop ran
• Each child node displays the same count as a ↻ N badge in its bottomRight slot
• Both numbers always match when the loop finishes

Scope

All canvas changes are isolated to the V2 story files. The original BaseNode.stories.tsx and LoopNode.stories.tsx are unchanged and serve as frozen reference.

Test plan

• Open Storybook → Canvas → BaseNode V2 → Anatomy — verify Loop Count Badge table renders
• Open Canvas → LoopNode V2 → Anatomy — verify all subsections present (Container Structure, Adornment Slots, Handles, V2 Iterations with Execution Count / Compound Picker / Progress Strip)
• Open Canvas → LoopNode V2 → Execution States V2 — interact with compound picker on each loop card; verify status dots, All aggregate, ⚠ jump-to-failed, and 1 px progress strip
• Confirm original Canvas → BaseNode and Canvas → LoopNode stories are visually unchanged

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