[gbdevw]

Summary

Adds unit tests for generic DID syntax parsing and for the public DID / DIDBuf accessors in crates/dids/core/src/did.rs. No production code changes.

Why

DID::new was only covered by 4 accept vectors and 3 reject vectors. A few ABNF cases that are easy to get wrong were untested, in particular consecutive colons in method-specific-id and malformed percent-encoding. The public accessors (method_name, method_specific_id, as_str, …) were also unexercised.

What

Accept:

• digits in the method name (did:m1:1)
• -, _ in the method-specific id
• lowercase percent-encoding (%af)
• consecutive colons (did:m::si:::1), allowed by
  method-specific-id = *( *idchar ":" ) 1*idchar

Reject:

• invalid scheme / method charset
• empty input, empty method, trailing colon
• incomplete or invalid pct-encoding (%, %0, %0G)
• DID URLs (/, ?, #) which are not DIDs

Accessors:

• as_str / as_bytes / method_name / method_specific_id (and *_bytes)
• Display and Deref on DID
• DIDBuf::from_string, as_did, to_owned round-trip
• consecutive colons are kept inside method_specific_id (":si:::1")

Notes

• Lowercase hex in pct-encoding is accepted on purpose: HEXDIG quoted strings are case-insensitive in RFC 5234, and RFC 3986 §2.1 treats %af and %AF as equivalent.
• Existing vectors (did:jwk:…, did:web:example.com%3A443:…) already cover . and uppercase ALPHA in the method-specific id.

[CLAassistant]

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