docs/jobq.md: drop the core-specific node table, keep only the abstract engine explanation

mara: "only the abstract jobq part was asked for in the first place" —
the previous revision still carried the full hive-c0re step-kind table
under a "core-specific nodes" heading; that catalogue belongs in
coordinator.md (where it already lived) alongside the rest of
hive-c0re's job-queue internals, not duplicated here.

jobq.md is now just the domain-agnostic model (graph of steps + shared
resource slots) plus the generic row/step/glyph framing for watching it
in the dashboard — no hive-c0re-specific step names anywhere.
Coordinator.md's job-queue section, docs/README.md, and the root
CLAUDE.md reading-paths index are updated to match.

docs/README.md

@@ -79,11 +79,10 @@ declarations.
 
 ## Scheduler, CI, observability
 
-- **What am I looking at in the build queue / R3BU1LD QU3U3? What does
-  each step mean?** → [`jobq.md`](jobq.md) — operator-facing, no
-  implementation detail.
-- **How does the rebuild queue work internally? What are queue kinds and
-  sources?** → [`coordinator.md`](coordinator.md).
+- **What is the job queue, as a general idea (not hive-c0re specifics)?** →
+  [`jobq.md`](jobq.md) — operator-facing, no implementation detail.
+- **How does the rebuild queue work? What are the concrete step kinds,
+  queue sources, scheduler internals?** → [`coordinator.md`](coordinator.md).
 - **How does the CI runner work? What's the auto-registration flow?** →
   [`ci.md`](ci.md).
 - **How do I export Claude Code metrics (tokens, cost, tool calls) to