refactor(cli): split EnrichCommand.enrichFromCache into phase helpers (RAN-41) (#73)

The 313-line enrichFromCache method scored cognitive complexity 94 on
SonarCloud (S3776, allowed 15) when PR #71 (RAN-23) re-classified it as
new code. Even small future edits in this file would re-trip the
new-code quality gate.

Extracted phases into private helpers, preserving exact ordering,
side effects, log lines, exit codes, and determinism:

  - applyGraphDirOverride        — --graph option handling
  - runLinkerPhase               — GraphBuilder + cross-file linkers
  - runClassifierAndEnrichers    — layer / lexical / language enrichment
  - runServiceDetection          — ServiceDetector + node/edge merge
  - bulkLoadIntoNeo4j            — top-level Neo4j orchestration
    - clearGraph                 — batched DETACH DELETE
    - bulkLoadNodes              — UNWIND CREATE in NODE_BATCH_SIZE batches
    - createPrimaryIndex         — id index + awaitIndexes
    - createStubNodesForExternalRefs / flushStubBatches / writeStubBatch
    - buildValidEdgeMaps / toEdgeProps
    - bulkLoadEdges              — UNWIND MATCH/CREATE batches
    - createSecondaryIndexes     — kind/layer/module/path/fulltext indexes
    - printCompletionSummary
    - shutdownQuietly            — finally-block dbms shutdown
  - logStepDone                  — shared "Done in Xms" line

Also lifted magic numbers (batch sizes, await timeout, progress interval,
stub-merge Cypher) into named constants and replaced fully-qualified
references (java.util.HashSet, ServiceDetector, ObjectMapper) with
imports for readability.

After refactor each method's cognitive complexity is well under 15
(orchestrator at ~1, largest helper at ~11).

Verification:
- mvn test -Dskip.npm=true → 3395 tests, 0 failures, 0 errors
- mvn spotbugs:check       → 0 findings
- EnrichCommandTest (4)    → still green

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: Paperclip <noreply@paperclip.ing>

Author: 3 people