refactor!: rebrand CCAM to AgentHub

Clean break, no compatibility alias. Renames the product name, the CLI
binary (`ccam` -> `agenthub`), the env var prefix (`CCAM_` ->
`AGENTHUB_`), the Prometheus metric namespace (`ccam_*` ->
`agenthub_*`), the tmux session prefix (`ccam-lane-<id>` ->
`agenthub-lane-<id>`), the per-repo runtime profile directory
(`.ccam/profile` -> `.agenthub/profile`), the lanes state root
(`~/.claude/ccam-lanes` -> `~/.claude/agenthub-lanes`), the bundled
plugins (`plugins/ccam*` -> `plugins/agenthub*`) and their slash
commands (`/ccam-doctor` -> `/agenthub-doctor`, `/ccam:*` ->
`/agenthub:*`).

Because there is no alias, an existing install has to be updated by
hand: rename its `.ccam/profile` directory and any `CCAM_*` variables,
and reinstall the plugin under its new name.

Two other name families are deliberately left alone here, since they are
not just strings: the `Claude-Code-Monitor` repository/marketplace name,
and the `agent-dashboard` npm package plus its `~/.claude/agent-dashboard`
runtime directory, which holds the live database and needs a migration
rather than a rename.

Verified: server 1406/1406, client 459/459, `grep -i ccam` clean across
tracked files, `openapi.yaml` regenerated (95 paths, unchanged count).

plugins/agenthub-analytics/hooks/hooks.json

@@ -0,0 +1,26 @@
+{
+  "hooks": {
+    "Stop": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "jq -r '{session_id: .session_id, stop_reason: .stop_reason, timestamp: now | todate}' | curl -s -X POST http://localhost:4820/api/hooks/event -H 'Content-Type: application/json' -d @- > /dev/null 2>&1 || true"
+          }
+        ]
+      }
+    ],
+    "SubagentStop": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "jq -r '{session_id: .session_id, agent_id: .agent_id, stop_reason: .stop_reason, timestamp: now | todate}' | curl -s -X POST http://localhost:4820/api/hooks/event -H 'Content-Type: application/json' -d @- > /dev/null 2>&1 || true"
+          }
+        ]
+      }
+    ]
+  }
+}