feat(workspace): split menus start AI tools; drop the Tools menu

A pane's split right/down menus offered only New terminal. They now list
the same AI tools as the tab bar's + menu (newTabTools/newTabBody,
shared from ConsoleTabs), started bare in the first free slot on that
side of the pane.

The tab bar's Tools menu is gone: its readme run hit 409 ERUNLIVE
whenever slot 0 was live (always, in the session view) and depended on
a personal skill; MCP sync and the dev-sync check served the dormant
ship-feature-lane pipeline. The sidebar row menu's readme item goes too.
The routes stay, reached by `agenthub lanes mcp sync` and
`agenthub lanes sync-base`.

Also: the home's Memory header and file tabs no longer shrink (a long
file squeezed the tab row and clipped it).

client/src/i18n/locales/en/lanes.json

@@ -7,16 +7,6 @@
   "action.stop": "stop",
   "actionError": "Workspace action failed: {{message}}",
   "actionErrorUnknown": "Unknown error",
-  "actions.busy": "…",
-  "actions.mcpSync": "Sync MCP",
-  "actions.mcpSyncResult": "Synced: {{servers}}",
-  "actions.syncCheck": "Check dev sync",
-  "actions.syncCheckClean": "DEV_DELTA: {{count}} file(s), overlap: {{overlap}}",
-  "actions.syncCheckCollision": "Migration collision: {{file}} → rename to {{suggestion}}",
-  "actions.tools": "Tools",
-  "actions.writeDocs": "Create/update readme file",
-  "actions.writeDocsHint": "Opens this workspace's terminal and runs /sg-all:sg-md-writing there: creates CLAUDE.md/AGENTS.md if missing, or updates them concisely if they already exist.",
-  "actions.writeDocsResult": "Started — see this workspace's terminal.",
   "add": "Add workspace",
   "addLane": "Create a workspace from a working directory",
   "addLaneBaseLabel": "Branch to fork from",