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-quality/commands/errors.md

@@ -0,0 +1,28 @@
+---
+description: List the most recent APIError events with their session and a summary
+argument-hint: "[N]"
+---
+
+List the most recent Claude Code errors from the Agent Monitor dashboard at
+`http://localhost:4820`. `$ARGUMENTS` is the number of errors to show (default 10).
+
+1. Pull recent events and keep only API errors:
+   ```bash
+   curl -s http://localhost:4820/api/events?limit=300
+   ```
+   Filter the array to `event_type == "APIError"`. (If `$ARGUMENTS` is a number,
+   show that many; otherwise show 10.) If none are found, also check
+   `curl -s http://localhost:4820/api/analytics` `event_types.APIError` to confirm
+   the true total and say "no recent APIError events (N total all-time)".
+
+2. For each error, newest first, print one line:
+   `timestamp · session_id · summary` — using the `timestamp`, `session_id`, and
+   `summary` fields exactly as returned (trim long summaries to ~100 chars).
+
+3. End with a one-line tally: total APIErrors shown and the most-affected
+   `session_id`.
+
+Output rules: cite only fields the API returned — never fabricate an error or a
+cause. Keep it to the list plus the tally; no extra prose. If `curl` cannot reach
+`http://localhost:4820`, tell the user to start the dashboard with `npm start`
+from the repo root.