docs: fix stale proof-suite claims in FABRIC-2.md; correct docs/CLAUDE.md's Makefile pointer

FABRIC-2.md item 5.2: both lemmas described as deliberately oops-flagged
(ROLL semantics, pipeline pm_wf invariant) were actually resolved
2026-08-13, same day, but FABRIC-2.md was never updated to match --
found during a docs-tree maintainability sweep. Corrected both, and
flagged a real untracked finding the pipeline fix surfaced: the Isabelle
model's accuracy num/den fraction pair doesn't correspond to the real
PipelineGlobalMetrics C struct at all. Also reconciled the theory-count
drift (53/54 mid-sweep numbers vs. the actual current 52, matching
proof/COVERAGE.md; proof/FINDINGS.md's own stale "53" flagged but not
fixed, out of this pass's scope).

docs/CLAUDE.md described a docs/Makefile with docs-formal/docs-working/
docs-index/docs-audit targets that doesn't exist anywhere in the tree.
The real build is docs/formal/Makefile with a completely different
target set (vol1/vol2/vol3/books/standalone/doxygen/clean) -- corrected
to match, and noted docs/INDEX.md has no automation and goes stale
between manual triage passes.

doxygen installed on this machine (was missing entirely, blocking the
API-reference build target).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/CLAUDE.md

@@ -42,15 +42,33 @@ is audience and stability, not quality.
 
 ## Makefile Targets
 
+**Corrected 2026-08-18** — this section previously described a `docs/Makefile` with
+`docs-formal`/`docs-working`/`docs-index`/`docs-audit`/`docs`/`docs-clean` targets. That file
+does not exist and none of those targets exist anywhere in the tree. The real build lives one
+level down, at `docs/formal/Makefile`, with a different target set entirely:
+
 ```
-make docs-formal     — build all three LaTeX volumes → PDFs in formal/build/
-make docs-working    — render working/ markdown to HTML (optional, low priority)
-make docs-index      — generate docs/INDEX.md inventory of all doc files
-make docs-audit      — list files tagged OBSOLETE or SUPERSEDED in INDEX.md
-make docs            — run docs-formal + docs-index
-make docs-clean      — remove formal/build/ artifacts
+# Run from docs/formal/
+
+make            — everything: all three volumes + books + standalone docs + doxygen
+make vols       — vol1 + vol2 + vol3 (the three-volume LaTeX set)
+make vol1       — Volume I only
+make vol2       — Volume II only
+make vol3       — Volume III only
+make books      — dev-guide + user-guide + cookbook
+make standalone — experiments + proofs + ssrn + patent (standalone LaTeX docs)
+make doxygen    — API reference PDF (requires the `doxygen` binary installed;
+                  runs doxygen → fix-doxygen-unicode.py → doxygen/latex → PDF)
+make clean      — remove build artifacts
 ```
 
+`docs/working/` has no build step of its own (no HTML rendering target exists) — it's read
+directly as markdown. `docs/INDEX.md` exists but is maintained manually, following this
+file's own Phase 1 triage process below — there is no `docs-index`/`docs-audit` automation
+that generates or checks it; treat `INDEX.md` as something a triage pass produces by hand,
+and expect it to go stale between passes (confirmed stale as of this correction — check its
+own date against `git log -1` before trusting it).
+
 ---
 
 ## Phase 1: Triage (DO THIS FIRST)