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).

server/lib/lane-profile.js

@@ -1,7 +1,7 @@
 /**
  * @file The stack seam. A profile is a repository's own description of how to
- * build, boot and check its stack: `<repo>/.ccam/profile/` holding a `profile.env`
- * of declarations plus a `hooks/` directory of shell scripts. CCAM stays
+ * build, boot and check its stack: `<repo>/.agenthub/profile/` holding a `profile.env`
+ * of declarations plus a `hooks/` directory of shell scripts. AgentHub stays
  * stack-agnostic and calls those hooks with a stable environment contract, which
  * is the same contract Shipyard's `run_hook` exports so its profiles port over
  * unchanged.
@@ -21,10 +21,10 @@ const { spawn } = require("node:child_process");
 const { slotDirs, dataFacts } = require("./lane-slots");
 
 /** Directory, relative to a repository root, holding its profile. */
-const PROFILE_SUBDIR = path.join(".ccam", "profile");
+const PROFILE_SUBDIR = path.join(".agenthub", "profile");
 
 /**
- * Hook names CCAM will run, ever.
+ * Hook names AgentHub will run, ever.
  *
  * A fixed allowlist rather than "whatever is in hooks/": `:name` arrives from an
  * HTTP route, and a name taken from a request is a path taken from a request.
@@ -197,7 +197,7 @@ function profileSearchPaths(lane) {
 
 /**
  * Whether a named integration is turned on for this lane — reads
- * .ccam/profile/integrations.env (same two-location search as profile.env:
+ * .agenthub/profile/integrations.env (same two-location search as profile.env:
  * the lane's own working copy first, the source repo second) and checks
  * <NAME>_ENABLED=1. A missing file or missing key is off, never an error —
  * same off-by-default shape every other optional declaration follows.