Spec update 2026-05-11 (merged namespace approach)

[AndreyVMarkelov]

Summary

• Generated from merged spec (Spec Update 05/11/2026 dropbox-api-spec#84)
• Each namespace is a single .stone file instead of many small files
• Produces functionally identical Rust SDK code

Compare with Bill Fraser's flat approach

Compare this PR with master...wfraser:dropbox-sdk-rust:spec_update_2026-04-21

Both approaches generate from the same source data (264 routes, 2291 types).
The merged approach simplifies the spec repo structure (23 files vs 95).

Test plan

• Compare generated types/routes between this PR and wfraser's branch
• Run cargo check to verify generated code compiles
• Verify route counts match between both approaches

🤖 Generated with Claude Code

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