feat: complete task editing coverage

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/diff.lua

@@ -43,7 +43,16 @@ function M.parse_buffer(lines)
       local stripped = body:match('^- %[.?%] (.*)$') or body
       local state_char = body:match('^- %[(.-)%]') or ' '
       local priority = state_char == '!' and 1 or 0
-      local status = state_char == 'x' and 'done' or 'pending'
+      local status
+      if state_char == 'x' then
+        status = 'done'
+      elseif state_char == '>' then
+        status = 'wip'
+      elseif state_char == '=' then
+        status = 'blocked'
+      else
+        status = 'pending'
+      end
       local description, metadata = parse.body(stripped)
       if description and description ~= '' then
         table.insert(result, {
@@ -117,7 +126,10 @@ function M.apply(lines, s, hidden_ids)
           task.category = entry.category
           changed = true
         end
-        if task.priority ~= entry.priority then
+        if entry.priority == 0 and task.priority > 0 then
+          task.priority = 0
+          changed = true
+        elseif entry.priority > 0 and task.priority == 0 then
           task.priority = entry.priority
           changed = true
         end