fix(ship-queue): wave plan links PRs only on a real code conflict and leaves out READY heads whose CI is not green (GST-770)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

docs/ship-policy.md

@@ -573,9 +573,15 @@ gstack-ship-queue wave settle --wave <nonce> [--dry-run]        # after the wave
 ```
 
 - **When.** `wave plan` counts the live READY PRs (open, head equal to their
-  READY receipt). Over the trigger (6) it prints `WAVE_ADVISED` and suggested
-  groups of 3 to 6: PRs that change a common file always share a group (their
-  conflicts are resolved once), each group takes its largest PR's functional
+  READY receipt, CI green at that head; a READY head whose CI is red or still
+  running prints a `NOT_GREEN` line and stays out of the plan). Over the
+  trigger (6) it prints `WAVE_ADVISED` and suggested groups of 3 to 6: PRs
+  whose changes to a common code file conflict (`git merge-tree` cannot merge
+  the two heads) always share a group, so that conflict is resolved once. Hub
+  files never link PRs: anything under `docs/`, Markdown and its `.tmpl`
+  sources, and JSON ledgers and registries. Most PRs append to them, and
+  linking through them once chained a 55-PR queue into a single area
+  (GST-770). Each group takes its largest PR's functional
   area (a skill directory, the first word of a `lib/`, `bin/` or `test/`
   module name, or `docs`), smaller groups ride solo, and the integrator is
   the PR with the most changed lines. `train build` handed more than 6 pins