release: prepare initial v0.1.0

[eareimu]

Summary

• align dhttp workspace release prep to the approved initial 0.1.0 line
• move ddns and h3x dependencies to their approved 0.3.0 release lines
• keep existing CI workflows unchanged

Release surfaces

• crates.io: initial user-owned publication
• npm (@genmeta/dhttp): initial user-owned publication
• PyPI (dhttpy): initial user-owned publication

Known wait conditions

• Publish crates.io is expected to stay red until same-wave upstream crates are visible on crates.io
• dhttp-identity 0.1.0 will be manually bootstrap-published by the user from an approved PR commit before upstream h3x dry-run can go green
• this PR intentionally does not modify dhttp CI/workflow behavior

Notes

• this PR is the release-prep branch for the initial dhttp wave
• merge/tag decisions remain gated on explicit user confirmation