fix: preserve reverse-proxy base path in SSH proxy URL

[kaiitunnz]

Purpose

When a FlowMesh server is deployed behind a reverse proxy that mounts it under a base path (e.g. reachable at example.com:8000/flowmesh), the SSH proxy connection instructions and the live proxy backend built a websocket URL with the base path stripped — wss://example.com:8000/api/v1/ssh/tasks/<id>/proxy instead of wss://example.com:8000/flowmesh/api/v1/ssh/tasks/<id>/proxy — so flowmesh ssh connect (and the copy-paste websocat command from flowmesh task watch) could not reach the proxy endpoint.

Changes

• sdk/src/flowmesh/ssh.py — ssh_proxy_url rebuilt the URL from urlsplit(base_url) keeping only the scheme and netloc, then hardcoded an absolute /api/v1/ssh/tasks/<id>/proxy path, discarding base.path. It now joins the configured base path with the API prefix ({base.path.rstrip('/')}{API_VERSION_PREFIX}/ssh/tasks/{task_id}/proxy), mirroring how _make_url composes REST URLs, and reuses the API_VERSION_PREFIX constant instead of re-hardcoding /api/v1. The http→ws / https→wss scheme conversion is unchanged.
• tests/sdk/test_resource_helpers.py — regression coverage: root-mounted base URL (no double slash), base-path preservation (/flowmesh), http→ws / https→wss conversion, trailing-slash handling, and a proxy-mode ssh_connection_commands case asserting the embedded ProxyCommand URL carries the prefix.

Design

The single ssh_proxy_url helper feeds both user-visible paths — the printed ProxyCommand=websocat … instructions in flowmesh task watch and the live flowmesh ssh proxy backend used by flowmesh ssh connect — so the one-line fix corrects both. base.path.rstrip('/') yields "" for a root-mounted server (preserving the existing /api/v1/... output with no leading double slash) and /flowmesh for a base-path deployment, including the trailing-slash form.

Test Plan

uv run pytest tests/ --ignore=tests/worker/test_mp_executor_cleanup_gpu.py
uv run pre-commit run --all-files

Test Result

• pytest tests/ --ignore=tests/worker/test_mp_executor_cleanup_gpu.py — all tests passed.
• pre-commit run --all-files — black / isort / ruff / codespell pass.

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Pre-submission Checklist

• I have read the contribution guidelines.
• I have run pre-commit run --all-files and fixed any issues.
• I have added or updated tests covering my changes (if applicable).
• I have verified that uv run pytest tests/ passes locally.
• If I changed shared schemas or proto definitions, I have checked downstream compatibility across Server and Worker.
• If I changed the SDK or CLI, I have verified the affected packages work.
• If this is a breaking change, I have prefixed the PR title with [BREAKING] and described migration steps above.
• I have updated documentation or config examples if user-facing behavior changed.

[timzsu]

LGTM.