Labeling strategies to reduce cardinality LP

[Eve832]

Adds a new learning path teaching a deliberate labeling strategy to
control cardinality and cost for metrics and logs in Grafana Cloud.

Milestones

1. business-value: why labeling strategy matters
2. understand-cardinality: active series, log streams, and how label values
   multiply; includes 4 new SVG diagrams
3. explore-your-cardinality (interactive): open the Cardinality tab in Cost
   Management and Billing and read the summary stats and both cardinality tables
4. metrics-labeling-strategy: metric label best practices, anti-patterns, and
   prevention at the source with relabeling
5. fix-metrics-cardinality (interactive): review Adaptive Metrics aggregation
   recommendations for existing cardinality
6. logs-labeling-strategy: fewest labels principle, structured metadata, and
   the label/metadata/log-line decision framework
7. correlate-dont-inflate: cross-signal pattern. keep metrics low cardinality,
   carry high cardinality detail on logs as structured metadata
8. end-journey: recap and links to related paths

Notes for reviewers

• All 8 packages pass Pathfinder CLI validation (validate --packages).
• Interactive selectors were verified against a live stack (learn.grafana.net):
  the CMB Cardinality tab test id and the Adaptive Metrics nav links.
• Product-behavior claims are cross-checked against published docs: 30-day
  cardinality retention, New/Unused badges, grafana-cmab-app.cardinality:read
  permission, 95th-percentile billing, 20-minute active-series window, and
  Adaptive Metrics compatibility guarantees.
• The four SVGs in assets/images/ might need to be uploaded to the grafana.com
  media library I'm not sure yet
• Adds me as the codeowner for /labeling-strategy-lj/

[github-actions]

💻 Deploy preview available (Labeling strategies to reduce cardinality LJ):

• https://deploy-preview-interactive-tutorials-452-zb444pucvq-vp.a.run.app/docs/learning-paths/

[JStickler]

This looks really useful (and I know we need this course!).

[tacole02]

Thanks for the PR. I smoke-tested the interactive milestones on learn.grafana.net shared in Block Editor, and those two steps worked.

This package is mostly conceptual content with only two Pathfinder-interactive milestones. That shape fits a Learning Hub journey, not an action-oriented Pathfinder path. Please keep the hands-on pieces as focused Pathfinder packages (along the lines of #484) and keep the broader labeling-strategy narrative in the website journey instead of merging this full path package.

I left a note on the path manifest. Please do not merge this PR in its current form.

[tacole02]

Most of this path is conceptual prose (understand cardinality, metrics/logs strategy, correlate signals). Only two milestones are hands-on in Pathfinder. We want Pathfinder packages to stay action-oriented. The conceptual journey you built belongs on the Learning Hub website side (same split as in #484 with the explore/reduce packages). Please do not merge this as a full Pathfinder learning path.