chore(tickets): réouverture #151 #157 + création epic slash-commands #161–#165

Réouvre #151 (résidu z-order bouton Cancel en état busy) et #157 (suivi UX :
arrêt du spinner à l'état terminal) en statut open avec assignations.
Crée l'epic slash-commands custom CLI : #161 (ombrelle suivi produit),
#162 (fondation registry + /help + /clean), #163 (UX autocomplete / menu),
#164 (/profile + reset session confirmé), #165 (commands contribées plugins).
nextNumber 161 → 166.

Bookkeeping tickets seul (l'état runtime .ideai hors-lot reste en working
tree, non committé).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.ideai/tickets/165/issue.md

@@ -0,0 +1,17 @@
+---
+id: "2b41b7d3-b362-4e8d-8c56-c92b429da1f7"
+number: 165
+title: "SDK/plugins: allow plugins to contribute custom CLI slash commands"
+status: "open"
+priority: "medium"
+sprint: null
+links: [{"target":"#162","kind":"dependsOn"}]
+agentRefs: [{"agentId":"b4730d7f-c54d-4736-8a04-c6203aa2fd49","role":"assigned"},{"agentId":"fe887179-933f-47d4-960f-c3b06827f86c","role":"assigned"}]
+attachments: []
+createdBy: {"kind":"agent","agent_id":"a6c6ea12-bfc6-4bdc-8031-324102dfa34d"}
+updatedBy: {"kind":"agent","agent_id":"a6c6ea12-bfc6-4bdc-8031-324102dfa34d"}
+createdAt: 1786017501962
+updatedAt: 1786018356463
+version: 3
+---
+Extend the SDK/plugin model so a plugin can contribute commands to the agent custom CLI slash-command system. Product decision: a plugin-contributed command is backed by a callback/function provided by the plugin, so the plugin can decide what the command actually does. Plugin commands must flow through the same unified registry/contract consumed by the frontend, with metadata sufficient for autocomplete and command execution. This ticket is about the extension seam and registration model, not the core native commands or the initial frontend menu.