fix: improve cache key quality across actions

Address cache key quality issues identified during code review.

php-composer:
- Remove unused cache-directories input and handling code
- Simplify cache paths to vendor + ~/.composer/cache only
- Eliminate empty path issue when cache-directories was default empty

npm-publish:
- Remove redundant -npm- segment from cache key
- Change: runner.os-npm-publish-{manager}-npm-{hash}
- To: runner.os-npm-publish-{manager}-{hash}

go-lint:
- Add ~/.cache/go-build to cached paths
- Now caches both golangci-lint and Go build artifacts
- Improves Go build performance

Result: Cleaner cache keys and better caching coverage

php-composer/rules.yml

@@ -2,7 +2,7 @@
 # Validation rules for php-composer action
 # Generated by update-validators.py v1.0.0 - DO NOT EDIT MANUALLY
 # Schema version: 1.0
-# Coverage: 56% (5/9 inputs)
+# Coverage: 50% (4/8 inputs)
 #
 # This file defines validation rules for the php-composer GitHub Action.
 # Rules are automatically applied by validate-inputs action when this
@@ -17,7 +17,6 @@ required_inputs:
   - php
 optional_inputs:
   - args
-  - cache-directories
   - composer-version
   - extensions
   - max-retries
@@ -25,18 +24,17 @@ optional_inputs:
   - token
   - tools
 conventions:
-  cache-directories: boolean
   composer-version: semantic_version
   max-retries: numeric_range_1_10
   php: semantic_version
   token: github_token
 overrides: {}
 statistics:
-  total_inputs: 9
-  validated_inputs: 5
+  total_inputs: 8
+  validated_inputs: 4
   skipped_inputs: 0
-  coverage_percentage: 56
-validation_coverage: 56
+  coverage_percentage: 50
+validation_coverage: 50
 auto_detected: true
 manual_review_required: true
 quality_indicators: