refactor(audit): remove dead DSL parser (DSL files no longer produced)

The v2 postfix DSL parser (DSL_WORD_ARITY_V2, _atom, to_dsl_v2, parse_dsl_v2)
was implemented during the 14-phase DSL plan but never reached production:
run_audit() (line ~1217 after this change) only writes .md files (AUDIT_REPORT.md
plus per-aggregate markdowns via to_markdown/to_tree), never .dsl files. The DSL
parser carried latent arity bugs (DSL_WORD_ARITY_V2 declared 5 for 'result-coverage'
but writer emits 4; 4 for 'type-alias-coverage' but writer emits 3) which would
have caused silent parse failures.

Also removed the now-unused 'import re' statement (was only used by parse_dsl_v2).
The 'from datetime import date as date_mod' is retained (still used at line ~1259,
1275, 1291 in the markdown renderer).

Tests deleted in lockstep:
- tests/test_code_path_audit_phase78.py: test_dsl_word_arity_v2_14_new_words
- tests/test_code_path_audit_phase89.py: test_to_dsl_v2_includes_aggregate_kind_section,
  test_parse_dsl_v2_round_trip_aggregate_kind, test_parse_dsl_v2_malformed

Verification:
- grep -c 'to_dsl_v2|parse_dsl_v2|DSL_WORD_ARITY_V2' src/code_path_audit.py = 0
- 127 of 127 remaining tests pass (was 131; -4 tests deleted)

tests/test_code_path_audit_phase89.py

@@ -21,10 +21,8 @@ from src.code_path_audit import (
  DecompositionCost,
  OptimizationCandidate,
  AggregateProfile,
- to_dsl_v2,
  to_markdown,
  to_tree,
- parse_dsl_v2,
  AGGREGATES_IN_SCOPE,
  CANDIDATE_AGGREGATES,
  synthesize_aggregate_profile,
@@ -56,14 +54,6 @@ def _make_profile(name: str = "Metadata", kind: str = "typealias") -> AggregateP
  )
 
 # Phase 8 Tasks 8.2-8.5 tests
-def test_to_dsl_v2_includes_aggregate_kind_section() -> None:
- """to_dsl_v2 emits the \\ === aggregate_kind === section."""
- profile = _make_profile()
- dsl = to_dsl_v2(profile, generated_date="2026-06-22")
- assert "\\ === aggregate_kind ===" in dsl
- assert '"typealias" kind' in dsl
- assert "\\ === memory_dim ===" in dsl
- assert '"discussion" mem-dim' in dsl
 
 def test_to_markdown_10_sections() -> None:
  """to_markdown emits the 10 sections per spec section 8.1."""
@@ -87,20 +77,6 @@ def test_to_tree_box_drawing() -> None:
  assert "Metadata" in tree
  assert "kind: typealias" in tree
 
-def test_parse_dsl_v2_round_trip_aggregate_kind() -> None:
- """parse_dsl_v2(to_dsl_v2(profile)) recovers the aggregate_kind section."""
- profile = _make_profile()
- dsl = to_dsl_v2(profile)
- parsed = parse_dsl_v2(dsl)
- assert isinstance(parsed, Result)
- assert "typealias" in str(parsed.data)
-
-def test_parse_dsl_v2_malformed() -> None:
- """parse_dsl_v2 returns Result.ok for empty input (no tagged words)."""
- result = parse_dsl_v2("\\ empty comment only\n")
- assert result.ok
- assert result.data == {"_sections": []}
-
 # Phase 9 Tasks 9.1-9.6 tests
 def test_aggregates_in_scope_10_real() -> None:
  """AGGREGATES_IN_SCOPE has 10 real aggregates."""