fix: resolve broken links across full codebase

[vdstrizhkova]

Description

Resolves all broken external and internal links detected by the SPELL_LYCHEE linter during a full codebase scan. Prior to this change, MegaLinter reported 59 link errors across 23 documentation files; after this fix the lychee linter exits with 0 errors.

Changes by category

Domain migration — principles.green → learn.greensoftware.foundation

• docs/design/sustainability/sustainable-engineering-principles.md — all seven principles.green URLs updated to equivalent paths on learn.greensoftware.foundation
• docs/design/sustainability/README.md — two remaining principles.green URLs updated

Dead external URLs replaced with working equivalents

File	Old URL	New URL
docs/automated-testing/cdc-testing/README.md	cloud.spring.io/spring-cloud-contract	docs.spring.io/spring-cloud-contract/docs/current/reference/html/
docs/automated-testing/synthetic-monitoring-tests/README.md	newrelic.com/products/synthetics	newrelic.com/platform/synthetics
docs/agile-development/advanced-topics/collaboration/pair-programming-tools.md	code.visualstudio.com/learn/collaboration/live-share	visualstudio.microsoft.com/services/live-share/
docs/observability/tools/loki.md	grafana.com/docs/loki/latest/getting-started/get-logs-into-loki/	grafana.com/docs/loki/latest/send-data/
docs/UI-UX/recommended-technologies.md	fast.design/docs/integrations#react	fast.design/docs/3.x/introduction/
docs/CI-CD/continuous-integration.md	leankit.com/learn/lean/principles-of-lean-development/	en.wikipedia.org/wiki/Lean_software_development
docs/code-reviews/recipes/markdown.md	plainenglish.co.uk/how-to-write-in-plain-english.html	www.plainenglish.co.uk/
docs/source-control/git-guidance/README.md	techoism.com/how-to-install-git-bash-on-windows/	gitforwindows.org/
docs/source-control/component-versioning.md	dead GitHub Gist for Angular commit conventions	conventionalcommits.org/en/v1.0.0/
CONTRIBUTING.md	plainenglish.co.uk/how-to-write-in-plain-english.html	www.plainenglish.co.uk/

Dead links removed (no replacement available)

• docs/design/diagram-types/ (README, class-, component-, deployment-, sequence-diagrams) — removed dead towardsdatascience.com link; plain text preserved
• docs/observability/observability-databricks.md — removed dead mspnp/spark-monitoring repo link (repository deleted); plain text preserved
• docs/code-reviews/recipes/java.md — replaced dead Azure SDK checkstyle blob URL with link to repo root

Broken internal link fixed

• docs/design/design-patterns/non-functional-requirements-capture-guide.md — corrected relative path ../../privacy/README.md → ../../non-functional-requirements/privacy/README.md

Lychee configuration (lychee.toml)

• Added .copilot-tracking and .projector to exclude_path (project-management files not part of the docs)
• Added bot-blocking domains to exclude list: goodreads.com, ranorex.com, dash.harvard.edu, tdurieux/anonymous_github — these are valid, live pages that return 503/429 for automated crawlers

PR Checklist

• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code follows the code style of this project.
• I ran the lint checks which produced no new errors nor warnings for my changes.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.

Does This Introduce a Breaking Change?

• Yes
• No

Testing

MegaLinter v8.1.0 run locally inside the devcontainer with VALIDATE_ALL_CODEBASE=true:

✅ Linted [MARKDOWN] files with [markdownlint]
✅ Linted [SPELL]    files with [cspell]
✅ Linted [MARKDOWN] files with [markdown-table-formatter]
✅ Linted [SPELL]    files with [lychee]          ← 0 errors (was 59)
✅ ACTION_ACTIONLINT
✅ YAML_PRETTIER
✅ YAML_YAMLLINT

OS: Debian GNU/Linux 11 (bullseye) inside dev container on macOS host.