feat(chat): Comments and review in VS Code, like the OpenChamber desktop app (#1724)

* feat(chat): render code comments as cards instead of fenced text

* fix(vscode): route Add Comment to the active session editor panel

* fix(chat): persist queued inline comments and tighten file-chip path matching

* feat(vscode): comment on code from the editor

* fix(chat): keep attached context in the message and broadcast comment removal

* fix(vscode): hold every pending comment and gate both entry points on the workspace

* fix(vscode): let only the owning surface decide its comment threads

* fix(vscode): drop a comment removed while its delivery was still in flight

* test(vscode): cover the in-flight comment removal guard

* test(vscode): cover comment removal reaching every chat surface

* fix(vscode): give up on a comment the chat never confirmed holding

* fix(vscode): retract a comment everywhere before reporting it discarded

* fix(chat): preserve queued comment cards

* fix: preserve inline comment context across send paths

* fix(chat): preserve command routing with context

* fix(chat): keep unavailable actions on normal send path

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Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/components/chat/composer/DOCUMENTATION.md

@@ -167,6 +167,16 @@ and the send path reading the same grammar.
   mention, file mentions, and skill instruction were resolved when it was
   queued, never at delivery — and its context follows it before the next
   queued message.
+- Local slash commands are planned by `submit/slashCommands.ts` before any
+  attached context is consumed. Commands that act on session or UI state
+  (`/undo`, `/redo`, `/compact`, `/timeline`, `/handoff-review`) take only
+  their command text and leave comments, files, and linked context attached;
+  commands that produce a prompt (`/btw` and the magic prompts) send that
+  context with the prompt they produce. Session actions are planned only when
+  a session exists, so typing one into a new-session draft stays on the normal
+  send path. A local command is never queued as text: queueing runs it
+  instead. A failed prompt command restores everything it consumed: text,
+  confirmed mentions, files, comment drafts, and pending synthetic context.
 - `state/useComposerDraft.ts` — a draft belongs to a (runtime, directory,
   session) identity. Writes are debounced while typing but forced at every edge
   where the page may stop running, because a pending timer is not a saved