fix(buffer): keep conceal active in all modes and add %l EOL forge labels

Problem: `concealcursor` was missing `i` and `v`, so concealed text
(task IDs, forge tokens) leaked in insert and visual modes. Forge
labels only rendered for the first span when multiple refs existed.

Solution: set `concealcursor = 'nicv'` to keep conceal in all modes.
Add `%l` EOL format specifier that renders all forge spans with
independent highlights. Update default `eol_format` to include `%l`.

lua/pending/config.lua

@@ -131,7 +131,7 @@ local defaults = {
   max_priority = 3,
   view = {
     default = 'category',
-    eol_format = '%c  %r  %d',
+    eol_format = '%c  %r  %d  %l',
     category = {
       order = {},
       folding = true,