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-dashboard/.claude-plugin/plugin.json

@@ -0,0 +1,17 @@
+{
+  "name": "agenthub-dashboard",
+  "description": "Direct MCP integration with the AgentHub dashboard — real-time session data access, quick stats, and dashboard health monitoring via Model Context Protocol.",
+  "version": "1.0.0",
+  "author": {
+    "name": "Nguyễn Ngọc Trí Vĩ",
+    "url": "https://git.smartgift.io.vn/Smartgift-AI"
+  },
+  "homepage": "https://git.smartgift.io.vn/Smartgift-AI/Claude-Code-Monitor",
+  "repository": {
+    "type": "git",
+    "url": "https://git.smartgift.io.vn/Smartgift-AI/Claude-Code-Monitor.git"
+  },
+  "license": "MIT",
+  "keywords": ["dashboard", "mcp", "connector", "real-time", "monitoring", "claude-code"],
+  "categories": ["integration", "mcp", "monitoring"]
+}