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).

client/src/pages/Workspace.tsx

@@ -461,7 +461,7 @@ export function Workspace() {
     }
   };
 
-  // Mirrors `ccam lanes pipeline <template> <id>`: same PATCH, same
+  // Mirrors `agenthub lanes pipeline <template> <id>`: same PATCH, same
   // stage-mismatch warning when the current declared stage matches no node
   // in the newly chosen template.
   const handlePipelineChange = async (id: number, pipeline: string) => {
@@ -470,7 +470,7 @@ export function Workspace() {
       const { lane } = await api.lanes.update(id, { pipeline });
       await refreshLanes();
       // `stage` defaults to the DB sentinel "idle" until a driving session ever
-      // calls `ccam stage` — that's the normal state for most lanes and never
+      // calls `agenthub stage` — that's the normal state for most lanes and never
       // matches a real pipeline node, so it isn't a mismatch worth surfacing.
       if (lane.stage !== "idle" && !lane.pipeline_nodes.some((n) => n.state === "current")) {
         setLaneActionError(
@@ -558,7 +558,7 @@ export function Workspace() {
           ))}
           {!lanes.length && (
             <p className="text-sm text-fg-muted">
-              {tLanes("emptyState")} <code>ccam lanes add --cwd $(pwd)</code>
+              {tLanes("emptyState")} <code>agenthub lanes add --cwd $(pwd)</code>
             </p>
           )}
         </div>
@@ -636,7 +636,7 @@ export function Workspace() {
                   ))}
                 </select>
                 {/* `stage` defaults to the DB sentinel "idle" until the driving
-                      session ever calls `ccam stage` — that string collides with
+                      session ever calls `agenthub stage` — that string collides with
                       `status`'s own "idle"/"running" vocabulary, so a lane that is
                       actively running but has never declared a stage read as if it
                       were sitting idle. Show a distinct label instead of the raw