perf: skip micromark + innerHTML for plain text without markdown syntax (#145)

[rohal12]

Summary

• Plain text fast path in renderNodes: After building the combined string, detect when text contains no markdown-triggering characters and build vnodes directly — bypassing both micromark and innerHTML. Eliminates ~655 innerHTML calls on plain UI text like "ALMA", "▸ Crew", "Activate" that pass through the full pipeline only to produce the same text they started with.
• Inline elements fix: Added INLINE_ELEMENTS set and inline option to markdownToHtml to disable block-level markdown constructs (lists, headings, blockquotes) inside inline HTML elements like <span>.
• Projected impact: Reduces click duration from 288ms to ~80-100ms for ALMA-like UI passages with nested HTML + {for} loops.

Detection

Conservative regex /[*_#|~[>\-+=]|![|\d+./covers all CommonMark + GFM syntax characters. Any false positive (text contains-` but not as a list item) harmlessly falls through to the existing micromark path. Zero risk to markdown rendering.

Test plan

• 24 correctness baseline tests (plain text, variables, Unicode, punctuation, non-nobr <p> wrapping)
• 13 fallthrough tests (all markdown syntax characters trigger full pipeline)
• Benchmark: ALMA-like UI ~5ms/render, 100 HTML elements ~3ms/render
• Full suite: 1121/1121 tests pass
• tsc --noEmit clean

Closes #145

🤖 Generated with Claude Code

[github-actions]

Release preview: merging this PR will publish v0.43.4 (patch bump from v0.43.3)

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	77.56%	2855 / 3681
🔵	Statements	76.54%	3116 / 4071
🔵	Functions	69.04%	513 / 743
🔵	Branches	73.64%	1559 / 2117

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/markup/markdown.ts	100%	100%	100%	100%
src/markup/render.tsx	91.11%	82.5%	100%	94.21%	87, 165, 230-236, 251-252, 263, 284, 285, 286, 290-291

Generated in workflow #224 for commit 3d0c96c by the Vitest Coverage Report Action