Emit warning when osrm-extract encounters ways referencing missing nodes

[afarber]

Issue

Fixes #1596

When an OSM file has <way> elements referencing <node> elements that don't exist, osrm-extract processes the file silently. Users get no indication their input data has problems, making it difficult to diagnose issues in later pipeline stages.

The extractor already handles this correctly at the code level -- PrepareNodes() filters out missing node references and PrepareEdges() marks edges with invalid nodes as SPECIAL_NODEID. However, the existing debug-level messages are only visible with --verbosity DEBUG.

This PR adds a logWARNING that is visible at the default log level.

Missing boundary nodes are expected for bounding-box extracts, so extraction still succeeds -- the warning simply informs the user about the count of dropped nodes.

Tasklist

• self-review code for correctness and following the coding guidelines
• add tests (see testing)
• update relevant wiki pages
• CHANGELOG.md entry (see how to)
• review
• adjust for comments

Requirements / Relations

None

[DennisOSRM]

The change looks good to me. I think I remember a discussion on the topic where someone raised a concern that this could turn into log spewing on planet files.

[Copilot]

Pull request overview

Adds a user-visible warning during extraction when OSM <way> elements reference missing <node> elements, improving diagnosability of malformed or clipped input data while keeping extraction successful.

Changes:

• Emit a logWARNING in ExtractionContainers::PrepareNodes() reporting how many referenced nodes were dropped as missing.
• Add a cucumber step to remove a node from generated OSM test data.
• Add a new feature test covering the warning behavior, plus a CHANGELOG entry.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/extractor/extraction_containers.cpp	Logs a warning when referenced nodes are missing after node intersection/filtering.
features/step_definitions/data.js	Adds a test step to remove a node from the synthetic OSM DB.
features/options/extract/missing_nodes.feature	New scenario asserting the warning appears on stderr for missing node references.
CHANGELOG.md	Documents the new extraction warning behavior.

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[afarber]

@DennisOSRM the warning is a single summary line with the count, not per-node, so it shouldn't spam the planet logs