fix(docker): entrypoint shim so child images with custom CMD work (#28)

v0.3.13 switched ENTRYPOINT to ["webclaw"] to make `docker run IMAGE
https://example.com` work. That broke a different use case: downstream
Dockerfiles that `FROM ghcr.io/0xmassi/webclaw` and set their own
CMD ["./setup.sh"] — the child's ./setup.sh becomes arg to webclaw,
which tries to fetch it as a URL and fails:

  fetch error: request failed: error sending request for uri
  (https://./setup.sh): client error (Connect)

Both Dockerfile and Dockerfile.ci now use docker-entrypoint.sh which:
- forwards flags (-*) and URLs (http://, https://) to `webclaw`
- exec's anything else directly

Test matrix (all pass locally):
  docker run IMAGE https://example.com     → webclaw scrape ok
  docker run IMAGE --help                   → webclaw --help ok
  docker run IMAGE                          → default CMD, --help
  docker run IMAGE bash                     → bash runs
  FROM IMAGE + CMD ["./setup.sh"]           → setup.sh runs, webclaw available

Default CMD is ["webclaw", "--help"] so bare `docker run IMAGE` still
prints help.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -3102,7 +3102,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-cli"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "clap",
  "dotenvy",
@@ -3123,7 +3123,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-core"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "ego-tree",
  "once_cell",
@@ -3141,7 +3141,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-fetch"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "bytes",
  "calamine",
@@ -3163,7 +3163,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-llm"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "async-trait",
  "reqwest",
@@ -3176,7 +3176,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-mcp"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "dirs",
  "dotenvy",
@@ -3197,7 +3197,7 @@ dependencies = [
 
 [[package]]
 name = "webclaw-pdf"
-version = "0.3.18"
+version = "0.3.19"
 dependencies = [
  "pdf-extract",
  "thiserror",