Make p paste as children and P as siblings below

After trying part 8c, the user found p and P doing the same thing on the
canvas: both pasted a sibling below the node (P only differed in the
outline's order). Their pick: p pastes under the node, as its last
children, the way a adds a child; P pastes the next siblings, below it,
where o adds one. ]p went away, since p does what it did.

Inside a title p and P still paste after and before the text cursor, as
in vim: they're their own commands (paste-after, paste-before), and the
node ones are paste-as-child and paste-as-sibling.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

DESIGN.md

@@ -157,9 +157,11 @@ lines.
 - A register holds text or nodes, and either pastes anywhere: nodes pasted
   into a text give their titles, text pasted on nodes becomes nodes. `yy`,
   `yab`, `yib` yank nodes; every delete (`dd`, `x`, `dib`, `d` on a
-  selection) keeps what it took, so `dd` then `p` moves a branch. `p` `P`
-  `]p` paste after, before, or as the last children, keeping the yanked
-  layout, where a new node would go; a count pastes copies. Links between
+  selection) keeps what it took, so `dd` then `p` moves a branch. `p`
+  pastes as the node's last children and `P` as its next siblings (the
+  user's pick after trying part 8c: `p` goes under the node as `a` adds,
+  `P` below it as `o` adds), keeping the yanked layout, where a new node
+  would go; a count pastes copies. Links between
   the pasted nodes come along, and so do links to nodes still there when
   they go back into the document they came from.
 - `"+` is the system clipboard. Nodes go there as Markdown, the user's
@@ -421,7 +423,7 @@ text).
 | **Move** (every view) | `hjkl` or arrows · `gh gj gk gl` tree moves · `w` `b` next / previous in reading order · `gg` root · `G` last · `/` `n` `N` search · `Ctrl-o` `Ctrl-i` (Tab) jump back / forward · `m{a-z}` `'{a-z}` marks (`A–Z` across documents) · Enter or `gf` through a portal · `gd` follow a cross-link |
 | **View** | `zz` center · `Ctrl-e` `Ctrl-y` `zh` `zl` pan · `Ctrl-d` `Ctrl-u` half a screen · `+` `-` zoom · `za zo zc zR zM` folds · `zf` Auto · `zi` focus · `K` body card |
 | **Create and edit** | `o` `O` sibling below / above · `a` child · `i` `A` Enter edit the title · `I` edit from its start · `cc` `S` retype |
-| **Operators** | `dd` or `dab` delete branch · `dib` delete children · `x` delete just the node · `yy` `yab` `yib` yank · `p` `P` paste after / before · `]p` paste as child · `>>` `<<` indent / outdent · `"a`–`"z` and `"+` registers · `.` repeat · `u` `Ctrl-r` undo / redo |
+| **Operators** | `dd` or `dab` delete branch · `dib` delete children · `x` delete just the node · `yy` `yab` `yib` yank · `p` paste as children · `P` paste as siblings below · `>>` `<<` indent / outdent · `"a`–`"z` and `"+` registers · `.` repeat · `u` `Ctrl-r` undo / redo |
 | **Modes** | `v` `V` visual · `M` move · `C` connect · `:` command · Esc back to normal |
 | **Leader** `<Space>` | `c` color · `s` style · `B` border · `t` tags · `p` new portal · `i` inbox · `b` documents · `v` then `c`/`o`/`n` for canvas / outline / note · `w` which-key on/off · `?` help |
 | **Panes, documents** | `Ctrl-w v` `Ctrl-w s` split · `Ctrl-w hjkl` focus · `Ctrl-w w` the next pane · `Ctrl-w c` close · `Ctrl-w o` only · `Ctrl-w =` even sizes · `gt` `gT` `]b` `[b` next / previous document · `ZZ` close pane (the last one quits) |