fix(sdk): rename Priority.NORMAL to MEDIUM to match server contract

[fatih-acar]

Summary

The Infrahub API backpressure layer renamed its middle X-Priority tier from normal to medium (opsmill/infrahub#9879) and now parses the header against enum member names. An SDK client emitting normal no longer matches any tier, so background flows (artifact generation, generators, diffs) crash with ValueError: 'medium' is not a valid Priority. This renames the SDK's Priority enum to keep the emitted header aligned with the server contract.

Key Changes

• The SDK now emits X-Priority: high | medium | low, matching the server's tiers — background workflows that carry a request priority no longer error.
• Priority.NORMAL → Priority.MEDIUM (wire value "normal" → "medium") in infrahub_sdk.constants. The feature is unreleased, so no backward-compatible NORMAL alias is kept.
• Config.priority description, the regenerated config.mdx reference, and the unreleased changelog fragment updated to high|medium|low.
• Priority / config / relogin unit tests updated for the new member and the pydantic validation message.
• The ihs-259 design docs under dev/specs/ re-titled normal → medium.

Related Context

Server-side counterpart: opsmill/infrahub#9879 (IFC-2886). The tier rename is documented in that PR's "Update since original description" section.

Documentation Updates

• docs/docs/python-sdk/reference/config.mdx regenerated.
• changelog/1151.added.md (unreleased X-Priority fragment) updated.
• dev/specs/ihs-259-sdk-x-priority-header/* design docs updated.

Test Plan

• uv run invoke format lint-code — ruff, ty, mypy clean.
• uv run invoke lint-docs — rumdl clean.
• uv run pytest tests/unit/sdk/test_priority.py tests/unit/sdk/test_config.py tests/unit/sdk/test_relogin_headers.py — 91 passed.
• CI to watch: validate-generated-documentation (the regenerated config reference is committed).

---

Summary by cubic

Renamed the SDK’s middle priority from NORMAL to MEDIUM and now emit X-Priority: high|medium|low to match the server contract. This fixes crashes in background workflows caused by the server expecting medium.

• Bug Fixes
  • Updated Priority enum in infrahub_sdk/constants.py: NORMAL → MEDIUM (wire value "medium").
  • Synced Config.priority docs and descriptions to high|medium|low.
  • Adjusted tests and validation messages to the new value.
  • Updated specs and the unreleased changelog.

^{Written for commit 3ba71b4. Summary will update on new commits.}

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@                 Coverage Diff                  @@
##           infrahub-develop    #1208      +/-   ##
====================================================
- Coverage             83.98%   83.17%   -0.82%     
====================================================
  Files                   139      139              
  Lines                 14390    12437    -1953     
  Branches               2381     1852     -529     
====================================================
- Hits                  12085    10344    -1741     
+ Misses                 1654     1528     -126     
+ Partials                651      565      -86     

Flag	Coverage Δ
integration-tests	40.29% <0.00%> (-2.39%)	⬇️
python-3.10	56.91% <0.00%> (-1.74%)	⬇️
python-3.11	56.91% <0.00%> (-1.74%)	⬇️
python-3.12	56.91% <0.00%> (-1.72%)	⬇️
python-3.13	56.93% <0.00%> (-1.72%)	⬇️
python-3.14	56.91% <0.00%> (-1.74%)	⬇️
python-filler-3.12	22.51% <100.00%> (-0.21%)	⬇️

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Files with missing lines	Coverage Δ
infrahub_sdk/config.py	91.46% <ø> (-3.30%)	⬇️
infrahub_sdk/constants.py	93.33% <100.00%> (-1.12%)	⬇️

... and 13 files with indirect coverage changes

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[cubic-dev-ai]

No issues found across 17 files

_{Re-trigger cubic}

[dgarros]

@fatih-acar this is already covered in #1205
I think we should close this one