F-090: project-global dependency validation exclusions

[stepango]

Summary

Implements F-090 / GH #97: allow-list forked-in monorepo modules (ExoPlayer-class) so they skip project-dependency suffix validation without weakening the default matrix or adding per-call-site escape hatches.

Changes

• dependencyValidationExclusions: Set<String> = emptySet() on root androidProjectConfiguration / AndroidProjectSettings
• Exact match on Gradle project path and/or name
• applyDependencies skips validator.validate only for excluded dependency projects; still adds the edge
• Self-type DSL validation unchanged; default empty = strict matrix unchanged
• Unit tests: :config matcher/store + :deps apply-gate
• Docs: DEPENDENCY-MATRIX.md, PROJECT-CONFIGURATION.md, GETTING-STARTED, README; sample commented example

Verify (host)

source scripts/env-mac.sh
cd plugins && ./gradlew :core:test :validation:test :deps:test :config:test build
cd ../application && ./gradlew help assembleDebug

Both BUILD SUCCESSFUL.

Ticket

• F-090 → done
• Next: F-091

Closes #97