Support uppercase tag filters for NIP-22 and other NIPs (#A-Z) #530

Request from Vitor Pamplona

Enable support for uppercase tag filters (#A-Z) in Nostream. NIP-22 comment threading specifically requires #i/#I filters for identifiers, but other NIPs also use uppercase variants.

NIP-22 Spec: https://github.com/nostr-protocol/nips/blob/master/22.md

Current Status

Nostream accepts only lowercase tag filters (#a-z):

• filter.ts: isGenericTagQuery() correctly validates both #a-z and #A-Z with regex /^#[a-zA-Z]$/ ✅
• filter-schema.ts: Validation at line 19 only accepts lowercase with regex /^#[a-z]$/ ❌

What's Missing

The filter schema validation needs to accept uppercase tag filters:

Current (line 19):

if (!knownFilterKeys.has(key) && !/^#[a-z]$/.test(key)) {

Should be:

if (!knownFilterKeys.has(key) && !/^#[a-zA-Z]$/.test(key)) {

This allows:

• NIP-22: #i/#I filters for comment threading identifiers
• NIP-22: #k/#K filters for kind scoping (comments vs events)
• NIP-22: #e/#E filters for event references
• NIP-22: #a/#A filters for addressable event references
• General: Any uppercase tag variant per Nostr convention

Acceptance Criteria

• Update filter-schema.ts to allow uppercase tag filters (#A-Z)
• Update documentation to explain tag filter scope (lowercase vs uppercase)
• Verify NIP-22 comment threading (kind 1111) works with proper tag filtering
• Add/verify NIP-22 in package.json supportedNips list