fix(server): recognize duration and time required as time aliases

[dubadub]

Summary

• The Cooklang spec defines time, duration, and time required as aliases for the canonical time metadata key (see cooklang-rs/src/metadata.rs:87), but the server's recipe and menu pages only looked up the literal time key, so recipes using either alias rendered no time pill.
• Add fallback lookups for duration and time required in both recipe_page and the menu handler, mirroring the existing alias pattern used for prep time / cook time.

Test plan

• cargo fmt, cargo clippy, cargo test clean
• Manually verified against cook server with three recipes (time:, duration:, time required:) — all three render the same ⏱️ <value> pill, no duplication under custom metadata

Closes #320

[claude]

Code Review — PR #342

Overview

Adds fallback lookups for duration and time required metadata aliases in recipe_page and menu_page_handler, matching the Cooklang spec's canonical alias definitions.

Code Quality

• Clean, minimal fix — exactly the right amount of change.
• Correctly mirrors the established .or_else() chain pattern already used for prep_time / cook_time aliases on the lines immediately below.
• Applied consistently in both locations that construct RecipeMetadata.

Potential Issues

• Missing location: There may be other RecipeMetadata construction sites. Worth a quick sanity-check to confirm these are the only two:

  grep -n 'RecipeMetadata {' src/server/ui.rs

  If there are others, they'll need the same fallback chain.
• Alias priority: The lookup order (time → duration → time required) is reasonable and matches the cooklang-rs canonical ordering. No change needed — just worth noting it's intentional.

Verdict

Looks good. The fix is correct, consistent with the existing code style, and closes the reported issue cleanly.