feat(feedback): add a /feedback command recorded through the command plane

Register a global `/feedback` command so a user can record a remark about the
session without spending a model turn. `/feedback <text>` acknowledges; empty
or whitespace-only input returns a usage error.

The plugin appends no session event of its own. `dsh-commands` already writes
a `command/run` / `command/done` pair for every dispatched command, carrying
the verbatim text and the settled outcome, and both records are log-only and
non-surface. The feedback is therefore durably in the session log and invisible
to the model without this package touching the log format.

Text is never parsed, so `/feedback /plan felt slow` records that literal
content. Nothing consumes the records; capture is deliberately inert.

New group `packages/feedback/` — no existing group owns feedback capture. Its
row raises the packages/README.md word ceiling by 10, which had no headroom;
one redundant sentence there was removed to offset most of the cost.

packages/feedback/command-feedback/package.json

@@ -0,0 +1,44 @@
+{
+  "name": "@deepseek-ai/dsh-command-feedback",
+  "description": "Human-facing slash command that records session feedback as a log-only event",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "main": "lib/index.js",
+  "types": "lib/types/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/types/index.d.ts",
+      "default": "./lib/index.js"
+    },
+    "./invariant": {
+      "types": "./lib/types/invariant.d.ts",
+      "default": "./lib/invariant.js"
+    },
+    "./src/*": "./src/*",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib/index.js",
+    "lib/invariant.js",
+    "lib/types/**/*.d.ts",
+    "lib/types/**/*.d.ts.map",
+    "src"
+  ],
+  "license": "BSD-3-Clause",
+  "peerDependencies": {
+    "@deepseek-ai/dsh-commands": "^0.0.1",
+    "@deepseek-ai/dsh-invariants": "^0.0.1",
+    "cordis": "^4.0.0-rc.7"
+  },
+  "devDependencies": {
+    "@cordisjs/plugin-include": "workspace:^",
+    "@cordisjs/plugin-loader": "workspace:^",
+    "@deepseek-ai/dsh-agent": "workspace:^",
+    "@deepseek-ai/dsh-commands": "workspace:^",
+    "@deepseek-ai/dsh-invariants": "workspace:^",
+    "@deepseek-ai/dsh-llm": "workspace:^",
+    "@deepseek-ai/dsh-session": "workspace:^",
+    "cordis": "^4.0.0-rc.7"
+  }
+}