Correct reading time calculation to avoid systematic overestimation

[plx]

Summary

readingTime currently adds an unconditional +1 minute before rounding, resulting in systematic overestimation.

Affected files:

• src/lib/utils.ts
• src/pages/blog/[...slug].astro
• src/pages/projects/[...slug].astro

Why This Matters

Displayed reading time is user-facing metadata and should be approximately accurate.

Proposed Strategy

• Update reading time formula to standard behavior: max(1, ceil(wordCount / 200)).
• Optionally normalize empty/very short content to 1 min read.
• Add focused unit tests for representative word counts (0, 1, 199, 200, 201, 399, 400).

Done Criteria / Validation

• readingTime no longer adds a blanket extra minute.
• Added tests cover edge cases and pass.
• npm run build passes.
• Sample long/short posts display expected values.