[WIP] Refactor parser infrastructure to eliminate excessive function line length

[Copilot]

• Fix rawloginlib violations in production code (add/rename logger vars)
  • pkg/parser/content_extractor.go - rename log.* → contentExtractorLog.*
  • pkg/parser/frontmatter_content.go - add logger var, replace log.*
  • pkg/parser/import_bfs.go - add logger var, replace log.*
  • pkg/parser/import_field_extractor.go - add logger var, replace log.*
  • pkg/parser/schedule_cron_detection.go - add logger var, replace log.*
  • pkg/parser/schema_errors.go - add logger var, replace log.*
  • pkg/parser/tools_merger.go - rename log.* → toolsMergerLog.*
  • pkg/actionpins/actionpins.go - rename log → actionPinsLog
• Fix largefunc violations in production code (extract helper functions)
  • import_bfs.go - processImportsFromFrontmatterWithManifestAndSource (492 lines)
  • schedule_fuzzy_scatter.go - ScatterSchedule (441 lines)
  • mcp.go - ParseMCPConfig (253), processBuiltinMCPTool (225), ExtractMCPConfigurations (193)
  • schedule_parser.go - parseBase (207), parseInterval (203)
  • include_processor.go - processIncludedFileWithVisited (166), processIncludesWithVisited (112)
  • schema_compiler.go - validateWithSchemaAndLocation (165)
  • import_topological.go - topologicalSortImports (157)
  • github_urls.go - ParseGitHubURL (134)
  • import_field_extractor.go - prepareFrontmatter (123), extractActivationFields (93), more
  • include_expander.go - ExpandIncludesWithManifest (87), processIncludesForField (62)
  • remote_fetch.go - downloadIncludeFromWorkflowSpec (101), ResolveIncludePath (85), more
  • frontmatter_content.go - ExtractFrontmatterFromContent (97)
  • yaml_import.go - processYAMLWorkflowImport (95)
  • json_path_locator.go - findAdditionalPropertyInNestedContext (77), findNestedSection (71)
  • frontmatter_hash.go - extractImportsFromText (74), marshalSorted (69)
  • schedule_time_utils.go - parseTime (82)
  • schema_suggestions.go - generateSchemaBasedSuggestions (81), generateExampleFromSchema (79)
  • tools_merger.go - MergeTools (80), mergeToolsFromJSON (62)
  • schema_errors.go - appendKnownFieldValidValuesHint (77)
  • sub_agent_extractor.go - ExtractInlineSubAgents (63)
  • actionpins/actionpins.go - ResolveActionPin (105)
• Fix largefunc violations in test files
• Run make golint-custom to confirm zero errors in pkg/parser/ and pkg/actionpins/
• Run tests to confirm no regressions