Support instances that serve SSH from another hostname

Discovery matched a git remote's host against the instance URL's host, so
a server answering SSH on a different name than its web UI resolved to
nothing — and said so only in a debug log.

Resolution now runs in three stages. A remote host is matched directly,
then against configured aliases, and failing both the instances are asked
for the repository: Gitea publishes its SSH hostname in a repository's
ssh_url, so the right instance identifies itself. What that turns up is
saved as a host alias, so later repositories on the same host resolve
with no lookup at all, and the mapping is visible and editable rather
than hidden. Each unknown host is probed at most once per session.

When nothing resolves the sidebar now names the unmatched host and offers
Add Host Alias, instead of showing an empty section.

Aliases can also be written by hand as "remote-host = instance URL",
accepting =, -> and =>, ignoring ports, and skipping # comments. List
preferences now merge workspace entries onto global ones rather than
letting an empty global array mask them.

Adds Tests/host-aliases.test.js covering both directions: unmatched hosts
reported and nothing persisted, a hand-written alias, detection from
ssh_url, and a later repository resolving from the stored alias without a
probe. 131 checks across three suites.

Also adds CLAUDE.md, and .gitea/workflows/ci.yml running the suites,
script syntax checks, manifest validation, and a generated-image check.
Tools/make-icons.py gains --check, which compares decompressed pixels so
a differing zlib version cannot fail it spuriously.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01MQuusXgZC2dzwpJJ1qhtti

.gitea/workflows/ci.yml

@@ -0,0 +1,51 @@
+#
+# Runs the test suites on every push and pull request.
+#
+# `runs-on` uses the label most Gitea runners register by default. If yours
+# registers something else, change it here — nothing in these jobs depends on a
+# particular image beyond node, python3, and git.
+#
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    name: Tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: Validate the extension manifest
+        run: node -e "JSON.parse(require('fs').readFileSync('extension.json', 'utf8'))"
+
+      - name: Syntax-check every script
+        run: find Scripts Tests -name '*.js' -print0 | xargs -0 -n1 node --check
+
+      # No install step: the Nova runtime and the Gitea server are both stubbed,
+      # and the git fixtures are built in temporary directories.
+      - name: Run the test suites
+        run: Tests/run.sh
+
+  images:
+    name: Generated images
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v4
+
+      # Images/ is generated from the shapes in Tools/make-icons.py. --check
+      # compares decompressed pixels rather than file bytes, so a different
+      # zlib version cannot fail this spuriously.
+      - name: Check the committed images match their source
+        run: python3 Tools/make-icons.py --check