feat(addons): add the PiKVM add-on

Chats and agents can check a PiKVM (kvmd) device and, when a person
confirms each call, press the power buttons of the machine it controls
and use its keyboard.

Read tools: get-info (model, versions, no serial or host name),
get-power-state (ATX LEDs) and get-keyboard-state. Write tools:
power-action (on, off, reset; off_hard, reset_hard and long_press only
with a per-device switch), type-text (bounded, no control characters,
refuses key, token and password-list shapes) and send-key (a short
allowlist, no Windows or Meta chords). All three declare approval
always. The preview reads the power state; apply reads it again and
rejects a stale operation. The add-on journals before it sends, never
retries and reports unknown when the connection drops.

One connection is one device: the address is the single resource of the
connection and the one sealed credential holds user:password, split at
the first colon. A one-time code is not supported. The add-on speaks
only to that address, refuses redirects, uses no proxy and accepts a
self-signed certificate only through a #sha256= pin in the address.
Typing, the text length and hard power actions are per-device switches
that an administrator sets on the add-on page; all start off. Snapshots,
mass storage, GPIO and the mouse are left out.

The add-on ships a skill, a connection page with a Test button and
approval cards, the package files, the library entry and the docs, and
joins the package workflow and the case inventory.

PiKVM API reference: https://docs.pikvm.org/api/

Assisted-by: Claude:claude-sonnet-5-5 go node

.github/workflows/addons-package.yml

@@ -117,7 +117,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        addon: [tables, voice, face, fine-tuning, quantization, studio, talk, telegram, slack, discord, github, home-assistant, jellyfin, office, sandbox, web, memory]
+        addon: [tables, voice, face, fine-tuning, quantization, studio, talk, telegram, slack, discord, github, home-assistant, jellyfin, office, pikvm, sandbox, web, memory]
     steps:
       - uses: actions/checkout@v7
         with:
@@ -236,7 +236,7 @@ jobs:
           # event it fails the plan. A missing or malformed platform file, or
           # any other error, fails the plan on every event.
           include='[]'
-          for id in tables voice face fine-tuning quantization studio talk telegram slack discord github home-assistant jellyfin office sandbox web memory; do
+          for id in tables voice face fine-tuning quantization studio talk telegram slack discord github home-assistant jellyfin office pikvm sandbox web memory; do
             cfg="addons/$id/package/platforms.yaml"
             err="matrix-$id.err"
             if rows=$(go run ./scripts/addons/cmd/addonpkg matrix --config "$cfg" 2>"$err"); then