docs: clear all 39 cold-build Sphinx warnings (truly green)

A `make docs-api-clean && make docs-api` cold rebuild now succeeds
with zero WARNING/ERROR lines (was 39).

Docstring fixes (RST hygiene — no semantic change):
- arborist/qa/{keys,runner,query,verify,quantifier,metacognition,dag,
  evidence}.py — add blank lines around indented blocks, convert
  ad-hoc indented sections to literal blocks (`::`), avoid line-broken
  inline literals (e.g. UNKNOWN_EVIDENCE_ID), and replace nested
  bracket/quote literals with cleaner wording.
- arborist/concepts/__init__.py — wrap function-signature listing in
  a literal block so bare `*` (kwarg marker) doesn't trip docutils.
- arborist/store.py — blank line before bullet lists in module +
  connect docstrings.
- arborist/evict.py — replace ad-hoc `{ ... }` enum block with prose.

Surface fixes:
- docs/_source/_ext/makefile_targets.py — escape `*` in auto-
  generated Makefile target descriptions (covers `*-parallel`,
  `*.dot`, `*.db`, `π*`, etc.) so the generator emits clean RST.
- docs/_source/index.rst, concepts.rst — extend title underlines
  to match title length.
- docs/_source/concepts.rst, v8-fork-score.rst — widen first column
  of grid tables so cells no longer overflow into the column margin.
- docs/_source/merkle-agi-v7w-spatial-temporal.rst — switch
  pseudocode JSON block from `code-block:: json` to `text` (the
  `<int32 x 3>` placeholders aren't valid JSON tokens).

Verification:
- make docs-api-clean && make docs-api → build succeeded, 0 warnings
- make test → 1588 passed, 28 skipped
- make chain-check-shards → 0 breaks across all 7 shards
- import-time SyntaxWarning escalation on edited modules → clean

docs/_source/_ext/makefile_targets.py

@@ -133,6 +133,13 @@ def parse_makefile(makefile_path: Path) -> dict[str, str]:
     return targets
 
 
+def _escape_rst(text: str) -> str:
+    # Bare `*` in description text (e.g. ``*-parallel``, ``*.db``,
+    # ``π*``) trips the docutils inline-emphasis scanner. Escape every
+    # asterisk so it renders literally.
+    return text.replace("*", r"\*")
+
+
 def generate_rst(all_targets: dict[str, str], output_path: Path) -> None:
     """Write a single RST page grouping every target by workflow phase."""
     lines = [
@@ -174,7 +181,7 @@ def generate_rst(all_targets: dict[str, str], output_path: Path) -> None:
         lines.append("     - Description")
         for name, desc in present:
             lines.append(f"   * - ``make {name}``")
-            lines.append(f"     - {desc}")
+            lines.append(f"     - {_escape_rst(desc)}")
         lines.append("")
 
     # Surface anything we forgot to categorize so it shows up in review.
@@ -196,7 +203,7 @@ def generate_rst(all_targets: dict[str, str], output_path: Path) -> None:
         lines.append("     - Description")
         for name, desc in sorted(leftover):
             lines.append(f"   * - ``make {name}``")
-            lines.append(f"     - {desc}")
+            lines.append(f"     - {_escape_rst(desc)}")
         lines.append("")
 
     output_path.write_text("\n".join(lines), encoding="utf-8")