feat(parse): extract forge refs from task body

Problem: `parse.body()` had no awareness of forge link tokens, so
`gh:user/repo#42` stayed in the description instead of metadata.

Solution: add `forge_ref` field to `pending.Metadata` and extend the
right-to-left token loop in `body()` to call `forge.parse_ref()` as
the final fallback before breaking.

lua/pending/parse.lua

@@ -6,6 +6,7 @@ local config = require('pending.config')
 ---@field rec? string
 ---@field rec_mode? 'scheduled'|'completion'
 ---@field priority? integer
+---@field forge_ref? pending.ForgeRef
 
 ---@class pending.parse
 local M = {}
@@ -596,7 +597,17 @@ function M.body(text)
               metadata.rec = raw_spec
               i = i - 1
             else
-              break
+              local forge = require('pending.forge')
+              local ref = forge.parse_ref(token)
+              if ref then
+                if metadata.forge_ref then
+                  break
+                end
+                metadata.forge_ref = ref
+                i = i - 1
+              else
+                break
+              end
             end
           end
         end