Fixed #140 -- Added route inject config validation before route registration.

[utk2103]

Summary

• Quater.add_route() now validates inject names/values at add time by routing through normalize_inject() inside
  build_route_definition(), matching RouteGroup's existing behavior.
• Dropped redundant normalize_inject() call in RouteGroup.add_route() since validation now lives in the shared builder.
• Added unit tests covering invalid inject parameter names and non-Resource inject values on Quater.add_route().
• Documented add-time validation in docs/en/dev/resources.md and recorded the change in docs/en/dev/changelog.md.

Linked Issue

Fixes #140

Contributor Checklist

• The linked issue was marked accepted before I started.
• Nobody else was assigned or already working on the issue before I started.
• My branch is named issue_{issue_number}.
• The PR is focused on one issue with no unrelated changes.
• Tests are added or updated when behavior changes.
• Docs are updated when user-facing behavior changes.
• Changelog is updated when the change is release-visible.
• I listed the checks I ran below.

Checks Run

• uv run pytest tests/unit/test_app_config.py -k "inject" -x — 2 passed
• uv run pytest tests/unit/test_route_group.py tests/unit/test_app_config.py — 131 passed
• uv run pytest tests/unit — 905 passed

[greptile-apps]

Greptile Summary

This PR moves route inject validation into the shared route builder. The main changes are:

• Quater.add_route() now validates invalid inject names and values at registration time.
• RouteGroup.add_route() now relies on the shared builder for the same validation.
• Unit tests cover app-level invalid inject names and non-Resource values.
• Resource docs and the changelog describe the earlier validation timing.

Confidence Score: 5/5

This looks safe to merge.

No blocking issues found in the changed code.

No files need follow-up.

T-Rex Logs

What T-Rex did

• Ran the inject-validation pytest suite and captured the run details in a log, including the command, working directory, selected pytest node names, EXIT_CODE: 0, and the summary 2 passed, 85 deselected.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
src/quater/_route_definition.py	Centralizes inject validation in the shared route-definition builder.
src/quater/groups.py	Removes duplicate route-level inject normalization from RouteGroup.add_route().
tests/unit/test_app_config.py	Adds app-level tests for invalid inject names and non-Resource values.
docs/en/dev/resources.md	Documents registration-time validation for route inject maps.
docs/en/dev/changelog.md	Records the route inject validation timing change.

_{Reviews (6): Last reviewed commit: "Fixed #140 -- Added route inject config ..." | Re-trigger Greptile}

[DevilsAutumn]

@utk2103 Thanks, just a small correction, rest everything looks correct.