fix: complete the docs/→design/ and openapi→api/ rename references

The file moves (docs/ → design/, docs/api/openapi.json → api/openapi.json) landed
in d01a8fd, but the matching reference updates did not — so mgmt.rs's drift-test
`include_str!("../../../docs/api/openapi.json")` pointed at a path that no longer
exists and the host failed to build. This restores it and updates every reference:

  - mgmt.rs include_str! → ../../../api/openapi.json (fixes the build)
  - web/orval.config.ts codegen target, web/Dockerfile, .dockerignore
  - deb/rpm/Arch packaging install paths
  - CLAUDE.md, the .gitea CI workflows, code doc-comments, design-doc cross-links

docs-site route URLs (/docs/...) untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/session_plan.rs

@@ -1,7 +1,7 @@
 //! `SessionPlan` — the per-session capture / topology / encoder decision, resolved **once** from
 //! [`HostConfig`](crate::config) (+ the handshake-negotiated bit depth) into a typed, logged value.
 //!
-//! **Goal-1 stage 3** (`docs/windows-host-rewrite.md` §2.2): before this, the Windows session decision was
+//! **Goal-1 stage 3** (`design/windows-host-rewrite.md` §2.2): before this, the Windows session decision was
 //! re-derived at three call sites — the capture backend inside `capture::capture_virtual_output`, the
 //! process topology in `punktfunk1::should_use_helper`, and the encode backend in
 //! `encode::windows_resolved_backend` — each reading [`config`](crate::config) independently, with no