feat: complete task editing coverage (#109)

Problem: the task editing surface had gaps — category and recurrence had
no keymaps, `:Pending edit` required knowing the task ID, tasks couldn't
be reordered with a keymap, priority was binary (0/1), and `wip`/`blocked`
states were documented but unimplemented.

Solution: fill every cell so every property is editable in every way.

- `gc`/`gr` keymaps for category select and recurrence prompt
- cursor-aware `:Pending edit` (omit ID to use task under cursor)
- `J`/`K` keymaps to reorder tasks within a category
- multi-level priorities (`max_priority` config, `g!` cycles 0→1→2→3→0)
- `+!!`/`+!!!` tokens in `:Pending edit`, `:Pending add`, `parse.body()`
- `PendingPriority2`/`PendingPriority3` highlight groups
- `gw`/`gb` keymaps toggle `wip`/`blocked` status
- `>`/`=` state chars in buffer rendering and diff parsing
- `PendingWip`/`PendingBlocked` highlight groups
- sort order: wip → pending → blocked → done
- `wip`/`blocked` filter predicates and icons

lua/pending/parse.lua

@@ -563,24 +563,34 @@ function M.body(text)
           metadata.cat = cat_val
           i = i - 1
         else
-          local rec_val = token:match(rec_pattern)
-          if rec_val then
-            if metadata.rec then
+          local pri_bangs = token:match('^%+(!+)$')
+          if pri_bangs then
+            if metadata.priority then
               break
             end
-            local recur = require('pending.recur')
-            local raw_spec = rec_val
-            if raw_spec:sub(1, 1) == '!' then
-              metadata.rec_mode = 'completion'
-              raw_spec = raw_spec:sub(2)
-            end
-            if not recur.validate(raw_spec) then
-              break
-            end
-            metadata.rec = raw_spec
+            local max = config.get().max_priority or 3
+            metadata.priority = math.min(#pri_bangs, max)
             i = i - 1
           else
-            break
+            local rec_val = token:match(rec_pattern)
+            if rec_val then
+              if metadata.rec then
+                break
+              end
+              local recur = require('pending.recur')
+              local raw_spec = rec_val
+              if raw_spec:sub(1, 1) == '!' then
+                metadata.rec_mode = 'completion'
+                raw_spec = raw_spec:sub(2)
+              end
+              if not recur.validate(raw_spec) then
+                break
+              end
+              metadata.rec = raw_spec
+              i = i - 1
+            else
+              break
+            end
           end
         end
       end