Caching hints (ttlMs / cacheScope)

[maxisbey]

Tracks: #2802

Emit ttlMs/cacheScope on the six cacheable results with a server-wide default and per-handler override; client just parses/exposes.

What's in it

• Server-wide default + per-handler override for ttlMs/cacheScope on tools/prompts/resources/templates list, resources/read, and discover.
• tools/list deterministic ordering (the SHOULD).
• Client parse/expose helper (wired in by New Client (all-versions, low-level + high-level) #2894).

Conformance

• caching
• Feeds the discover handler in Capabilities API + server/discover handler #2896

Dependencies

• Depends on: none

References

• Caching
• SEP-2549
• server/caching.ts