~anthropic/claude-sonnet-latest → A (60:40)

Commit A fixes a real routing/identity design issue (single opaque `/r/{short}{slug}` segment with validated round-trip helpers plus updated route wiring and tests) and adds a genuinely useful URL-identity normalization layer (query sorting, YouTube canonicalization) with substantial test coverage across multiple call sites (nav, search, write_actor, integration tests). Commit B is a clean, well-tested feature addition (RoomList RPC + CLI + isolation tests) but is narrower in scope and lower architectural impact than A's cross-cutting correctness fix.