docs(adr): finalize ADR-0058 number for clause-concept-hints

Rename the placeholder draft to its reserved number (0058, allocated
reserve-first via the new dev-workflow flow), drop the ADR-XXXX
placeholders, and add the README index row.

docs/adr/0058-clause-concept-hints.md

@@ -1,13 +1,13 @@
-# ADR-XXXX: Clause-concept hints — a `hint.concept.*` layer surfaced by cursor position (issue #37)
+# ADR-0058: Clause-concept hints — a `hint.concept.*` layer surfaced by cursor position (issue #37)
 
 ## Status
 
-Draft — **implemented 2026-06-23** on branch `feat/clause-concept-hints`
+Accepted — **implemented 2026-06-23** on branch `feat/clause-concept-hints`
-(pending merge). Number assigned at merge-to-`main` per ADR-0000
+(pending merge). Number **0058**, reserved up front via the reserve-first
-"Numbering discipline" (drafted under `draft-clause-concept-hints.md` /
+flow (ADR-0059) rather than the older placeholder-until-merge default —
-`ADR-XXXX`; README index entry added at merge). Extends **ADR-0053**
+this ADR is the first to carry a number stable from creation. Extends
-(contextual `hint`, D3/D4) additively; does not supersede it. Closes the
+**ADR-0053** (contextual `hint`, D3/D4) additively; does not supersede it.
-deferred extension tracked as Gitea issue **#37**.
+Closes the deferred extension tracked as Gitea issue **#37**.
 
 Implementation: `Node::Concept { topic, inner }` (`dsl/grammar/mod.rs`) +
 the span-recording driver arm (`dsl/walker/driver.rs`) +