fix(plugins): complete steward rename across bundled plugins; clear lint debt

The fabledscryer->steward rename had only ever reached host_agent. The other
five bundled plugins (http, snmp, traefik, unifi, docker) still imported
`from fabledscryer.*` (package no longer exists) and read FABLEDSCRYER_* env
vars — so every one of them was broken at import since the original rebrand.
CI stayed green only because none are enabled by default and migrations don't
import plugin modules. Now that they version in-tree, complete the rename:
- fabledscryer.* -> steward.* imports across all five plugins
- FABLEDSCRYER_* -> STEWARD_* in plugin migration env.py files
- author/repository/homepage + user-facing 'Fabled Scryer' strings -> Steward
- snmp/scheduler.py: also drop dead `now`/datetime; record_metric from steward

Adds tests/test_no_legacy_names.py — fails if 'scryer'/'roundtable' ever
reappear in shipped code (the drift bit twice; this stops a third time).

Also clears pre-existing ruff lint debt (unused imports, semicolon statements,
mid-file import) surfaced by the new lint lane.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/index.yaml

@@ -1,6 +1,6 @@
-# fabledscryer-plugins / index.yaml
+# steward-plugins / index.yaml
 #
-# Plugin catalog for Fabled Scryer.
+# Plugin catalog for Steward.
 # Fetched by the app at: Settings → Plugins → Plugin Catalog
 #
 # After updating an entry, commit and push — changes are live within 5 minutes
@@ -16,12 +16,12 @@ plugins:
   - name: http
     version: "1.0.0"
     description: "Synthetic HTTP endpoint monitoring — status code, response time, content match, TLS expiry"
-    author: "FabledScryer"
+    author: "Steward"
     license: "MIT"
     min_app_version: "0.1.0"
-    repository_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins"
-    homepage: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/src/branch/main/http"
-    download_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/releases/download/http-v1.0.0/http.zip"
+    repository_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins"
+    homepage: "https://git.fabledsword.com/bvandeusen/Steward-plugins/src/branch/main/http"
+    download_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins/releases/download/http-v1.0.0/http.zip"
     checksum_sha256: ""
     tags:
       - monitoring
@@ -32,12 +32,12 @@ plugins:
   - name: docker
     version: "1.0.0"
     description: "Docker container status, resource usage, and restart tracking via Docker socket"
-    author: "FabledScryer"
+    author: "Steward"
     license: "MIT"
     min_app_version: "0.1.0"
-    repository_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins"
-    homepage: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/src/branch/main/docker"
-    download_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/releases/download/docker-v1.0.0/docker.zip"
+    repository_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins"
+    homepage: "https://git.fabledsword.com/bvandeusen/Steward-plugins/src/branch/main/docker"
+    download_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins/releases/download/docker-v1.0.0/docker.zip"
     checksum_sha256: ""
     tags:
       - containers
@@ -47,12 +47,12 @@ plugins:
   - name: traefik
     version: "1.0.0"
     description: "Traefik reverse proxy metrics and access log integration"
-    author: "FabledScryer"
+    author: "Steward"
     license: "MIT"
     min_app_version: "0.1.0"
-    repository_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins"
-    homepage: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/src/branch/main/traefik"
-    download_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/releases/download/traefik-v1.0.0/traefik.zip"
+    repository_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins"
+    homepage: "https://git.fabledsword.com/bvandeusen/Steward-plugins/src/branch/main/traefik"
+    download_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins/releases/download/traefik-v1.0.0/traefik.zip"
     checksum_sha256: ""
     tags:
       - proxy
@@ -62,12 +62,12 @@ plugins:
   - name: unifi
     version: "1.0.0"
     description: "UniFi Network controller integration — WAN health, devices, clients, DPI"
-    author: "FabledScryer"
+    author: "Steward"
     license: "MIT"
     min_app_version: "0.1.0"
-    repository_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins"
-    homepage: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/src/branch/main/unifi"
-    download_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/releases/download/unifi-v1.0.0/unifi.zip"
+    repository_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins"
+    homepage: "https://git.fabledsword.com/bvandeusen/Steward-plugins/src/branch/main/unifi"
+    download_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins/releases/download/unifi-v1.0.0/unifi.zip"
     checksum_sha256: ""
     tags:
       - network
@@ -77,12 +77,12 @@ plugins:
   - name: ups
     version: "1.0.0"
     description: "UPS monitoring via NUT (Network UPS Tools) with Ansible shutdown automation"
-    author: "FabledScryer"
+    author: "Steward"
     license: "MIT"
     min_app_version: "0.1.0"
-    repository_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins"
-    homepage: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/src/branch/main/ups"
-    download_url: "https://git.fabledsword.com/bvandeusen/FabledScryer-plugins/releases/download/ups-v1.0.0/ups.zip"
+    repository_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins"
+    homepage: "https://git.fabledsword.com/bvandeusen/Steward-plugins/src/branch/main/ups"
+    download_url: "https://git.fabledsword.com/bvandeusen/Steward-plugins/releases/download/ups-v1.0.0/ups.zip"
     checksum_sha256: ""
     tags:
       - ups