docs(#54): F-4 legacy annotation + F-5 fixture convention -- AUDIT-01 housekeeping

INTEGRATION-AUDIT-01 (#50) §10.4 / §10.5 housekeeping carry-over.

F-4: annotate 14 remaining legacy Phase R'/Q sample-text hits across 10
src/ files with inline marker `# [legacy Phase R'/Q example -- INTEGRATION-AUDIT-01 §10.4]`.
Comment-only. No string-literal / regex / sample dict value mutated.
fit_verifier.py L612 marker keeps Phase Z partial-live import graph
(FitAnalysis / RoleFit / redistribute / salvage) byte-precise.

F-5: docs-only addendum -- §10.5.1 in INTEGRATION-AUDIT-01-REPORT.md +
tests/CLAUDE.md fixture convention note. No root tests/fixtures/ dir
created; existing tests/phase_z2/fixtures/ convention preserved. Documents
test-only sample-reference allowance vs src/** runtime prohibition.

Out of scope: Phase Z source 11 hits (phase_z2_content_extractor /
failure_router / mapper / retry), production behavior change, #19 work.

Verified: pytest -q tests/phase_z2/ = 157 PASS. git diff +210/-0
(35 src/docs lines + 175 new tests/CLAUDE.md). No behavioral delta.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/fit_verifier.py

@@ -609,6 +609,7 @@ class SupplementBlock:
     role: str
     block_id: str
     variant: str
+    # [legacy Phase R'/Q example — INTEGRATION-AUDIT-01 §10.4]
     content_source: str      # "popup:DX와 BIM의 구분" 등
     estimated_height_px: float
     available_px: float