badges: hide the Source badge when the source has no panel of its own

A Source pill that opens nothing (UDPS, Flat UDP, files) was noise. It is now shown only while the slide-over has a source page; the [badges] source line gains visible=.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/claude/verification.md

@@ -473,12 +473,13 @@ precedent, not an exception.
   **The source kind's panels are slide-over pages too** (`source-<id>`: the E-1608's `source-ao` and
   `source-dio`, Flat UDP's, the probe kind's), so the same rule holds for them. The probe appends a second
   `[badges]` line for the Source badge: `[badges] source name=<kind> pages=<n>
-  switch_visible=<0|1> can_target=<0|1> second_page=<id|-> second_ok=<0|1> open_marked=<0|1|-1>
+  visible=<0|1> switch_visible=<0|1> can_target=<0|1> second_page=<id|-> second_ok=<0|1> open_marked=<0|1|-1>
   closed_unmarked=1`. `pages` is the number of source pages, `switch_visible` is the segmented switch
   being on screen after the first source page was opened (`1` for the E-1608's two pages, `0` for one page
   or none), `second_page` is what `slideover_page()` read after the switch selected the second page
-  (`second_ok=1` when it is that page), `can_target=0` with `pages=0` is the UDPS badge being a read-out and
-  `open_marked=-1` is that no-page case (there is nothing to open).
+  (`second_ok=1` when it is that page), `visible=0` with `pages=0` is the UDPS badge being **hidden** (a kind with no source page
+  has nothing for it to open; `can_target=0` goes with it) and `open_marked=-1` is that no-page case (there is
+  nothing to open); `visible=1` with `pages>0`.
 - `UDPSCOPE_PROBE_SOURCE_KINDS=2000` with `UDPSCOPE_EXIT_AFTER_MS=5000`, run as `--source probe --source-opt rate=500`
   -- the source-plugin path end to end. The variable's presence also registers the test-only `probe` kind (a
   synthetic sine with one panel), so it is the only way a run sees that kind; its value is the delay in ms.