Fix: use deterministic IDs for code block copy buttons

[danielledeleo]

Summary

• Replaces now.UnixNano-based element IDs with a simple ordinal counter
• Applies to both render-codeblock.html (fenced code blocks) and ghcode.html (shortcode)
• Verified across two consecutive clean builds of a 620-page site: all 1,570 output files produce identical hashes

Problem

Code block copy buttons were assigned IDs like id-18a245ee1c0763ad using the wall-clock nanosecond timestamp at render time. This made HTML output non-deterministic — 40 out of 1,571 files differed between clean rebuilds of unchanged source, breaking content-addressable caching, diffing, and reproducible deployments.

Solution

// Before
{{ $codeBlockId := printf "id-%x" (now.UnixNano) }}

// After (render-codeblock.html)
{{ $codeBlockId := printf "cb-%d" .Ordinal }}

// After (ghcode.html)
{{ $codeBlockId := printf "gh-%d" .Ordinal }}

.Ordinal is Hugo's zero-based per-page counter. Different prefixes (cb- vs gh-) prevent collisions if both templates are used on the same page. Output IDs are clean and readable: cb-0, cb-1, cb-2, etc.

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[github-actions]

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