fix(plugins): make the 10 focused plugins installable, finish the AgentHub rename

The ten `agenthub-*` plugins were listed by the marketplace but could never be
installed — two schema mistakes present since the entries were first authored
(57dc915), both invisible until you actually run `claude plugin install`:

- marketplace entries used `"path": "plugins/<name>"`; the CLI only accepts
  `"source"`, so every one failed with
  `This plugin's marketplace entry is invalid: source: Invalid input`
- each `plugin.json` carried npm's `"repository": { "type", "url" }` object;
  the schema wants a plain string, so the next attempt failed with
  `Validation errors: repository: Invalid input`

Verified by installing all 11 entries into a throwaway CLAUDE_CONFIG_DIR:
1/11 before, 11/11 after. `plugins-marketplace.test.js` was asserting the
broken shape, which is why CI stayed green — it now asserts `source` and
rejects `path`.

Marketplace renamed `claude-code-agent-monitor-plugins` -> `agenthub`, so the
install line is `agenthub@agenthub`. ARCHITECTURE.md documented a marketplace
name (`smartgift-claude-code-monitor`) that never existed in any revision.

The documented `/plugin marketplace add Smartgift-AI/Claude-Code-Monitor` also
never worked: the `owner/repo` shorthand resolves to github.com only, and this
repo is self-hosted on Gitea. Confirmed the CLI rejects `host/owner/repo` and
ignores GH_HOST / GITHUB_HOST / CLAUDE_CODE_MARKETPLACE_URL, so the full
https:// clone URL is the only supported form. Same GitHub-habit class fixed
elsewhere: raw.githubusercontent.com icon URLs (404, and the repo ships
favicon.svg not favicon.ico — the client had the same dead /favicon.ico),
a smartgift.github.io docs link (404), and Gitea `/blob/<ref>/` paths that
must be `/src/branch/<ref>/`.

Repository renamed to Smartgift-AI/AgentHub throughout. Gitea 301-redirects
the old name, so these were stale rather than broken; `docs/superpowers/`
keeps the old name because those are dated decision records.

Adds `repo-links.test.js` to guard both classes (it runs under the existing
pre-commit gate) plus an openapi.yaml drift check — the committed spec had
silently fallen a minor version behind package.json. `generate-openapi-yaml.js`
now exports `render()` so the test compares against one definition of the dump
options instead of a second copy.

server/openapi-extra/override-sessions-agents.js

@@ -43,7 +43,7 @@ const exampleSession = {
   id: "b7f3a2c1-4e5d-4a8b-9c2f-1d6e8a0b3c4d",
   name: "Refactor pricing route + add cost endpoint",
   status: "active",
-  cwd: "/Users/son/WebstormProjects/Claude-Code-Agent-Monitor",
+  cwd: "/Users/dev/AgentHub",
   model: "claude-opus-4-20250514",
   started_at: "2026-06-25T14:02:11.004Z",
   ended_at: null,
@@ -60,7 +60,7 @@ const exampleCompletedSession = {
   id: "1a2b3c4d-5e6f-4071-8293-a4b5c6d7e8f9",
   name: "Fix flaky transcript pagination test",
   status: "completed",
-  cwd: "/Users/son/WebstormProjects/Claude-Code-Agent-Monitor",
+  cwd: "/Users/dev/AgentHub",
   model: "claude-sonnet-4-20250514",
   started_at: "2026-06-24T09:12:00.000Z",
   ended_at: "2026-06-24T09:48:32.501Z",
@@ -176,7 +176,7 @@ const paths = {
             example: {
               id: "b7f3a2c1-4e5d-4a8b-9c2f-1d6e8a0b3c4d",
               name: "Refactor pricing route + add cost endpoint",
-              cwd: "/Users/son/WebstormProjects/Claude-Code-Agent-Monitor",
+              cwd: "/Users/dev/AgentHub",
               model: "claude-opus-4-20250514",
               metadata: { source: "hook", git_branch: "feat/spend-budgets" },
             },