ci: new ci-runner base image + uv/ruff/node_modules cache

Runner base image (infra/Dockerfile.runner-base):
- Added uv (fast Python package installer, ~10x faster than pip)
- Added ruff (baked in, lint job drops from ~13s to ~2s)
- Added jq + tzdata
- Renamed tag from py3.12-node22 to ci-runner (purpose over contents)

Workflow (ci.yml):
- typecheck: cache node_modules directly instead of npm download cache;
  skip npm ci entirely on cache hits (9m41s → ~30s expected)
- lint: just `ruff check src/` — no venv, no install
- test: uv venv + uv pip install replaces pip (~10x faster resolves)
- all jobs: runs-on ci-runner label

Baseline: typecheck 9m41s, lint 13s, test 1m42s

infra/Dockerfile.runner-base

@@ -1,26 +1,28 @@
 # Runner base image for Forgejo act_runner job containers.
-# Pre-installs Python 3.12 and Node 20 so the test job skips the
-# ~3-4 minute deadsnakes PPA install on every run.
+# Pre-installs Python 3.12, Node 22, uv, and ruff so workflows skip
+# lengthy runtime installs on every run.
 #
-# Build and push (one-time setup, re-run if this file changes):
+# Build and push (re-run when this file changes):
 #   docker build -f infra/Dockerfile.runner-base \
-#     -t git.fabledsword.com/bvandeusen/runner-base:py3.12-node22 .
-#   docker push git.fabledsword.com/bvandeusen/runner-base:py3.12-node22
+#     -t git.fabledsword.com/bvandeusen/runner-base:ci-runner .
+#   docker push git.fabledsword.com/bvandeusen/runner-base:ci-runner
 #
-# Then redeploy the act_runner stack in Portainer to pick up the new label.
+# Then redeploy the act_runner stack in Portainer to pick up the new image.
 
 FROM ubuntu:24.04
 
 ENV DEBIAN_FRONTEND=noninteractive
+ENV TZ=UTC
 
-# Split into separate RUN steps so each pushed layer is smaller.
-# One combined layer would be ~280MB and exceeds the nginx upload timeout.
+# Split into separate RUN steps so each pushed layer is smaller — one
+# combined layer exceeds the nginx upload timeout on the self-hosted
+# Forgejo registry.
 
-# Python 3.12 ships in Ubuntu 24.04 main repos — no PPA needed.
+# Python 3.12 (ships in Ubuntu 24.04 main repos) + core tools
 RUN apt-get update -qq && \
     apt-get install -y -qq \
-      python3.12 python3.12-dev python3.12-venv python3-pip \
-      git curl ca-certificates gnupg && \
+      python3.12 python3.12-dev python3.12-venv \
+      git curl ca-certificates gnupg jq tzdata && \
     apt-get clean && rm -rf /var/lib/apt/lists/*
 
 # Node 22 LTS via NodeSource
@@ -33,3 +35,14 @@ RUN curl -fsSL https://deb.nodesource.com/setup_22.x | bash - && \
 RUN apt-get update -qq && \
     apt-get install -y -qq docker.io && \
     apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# uv — fast Python package installer/resolver (~10x faster than pip).
+# Used by test jobs instead of pip for venv creation + dep installs.
+RUN curl -LsSf https://astral.sh/uv/install.sh | env INSTALLER_NO_MODIFY_PATH=1 sh && \
+    mv /root/.local/bin/uv /usr/local/bin/ && \
+    mv /root/.local/bin/uvx /usr/local/bin/
+
+# ruff — Python linter. Baked in so the lint job is just
+# `ruff check src/` with zero install overhead.
+RUN curl -LsSf https://astral.sh/ruff/install.sh | env INSTALLER_NO_MODIFY_PATH=1 sh && \
+    mv /root/.local/bin/ruff /usr/local/bin/