fix: make .dockerignore ignore node_modules at any depth

[RudrenduPaul]

Closes #1920

What this PR does

Fixes a .dockerignore pattern that was written assuming .gitignore
semantics, which Docker does not follow.

Root cause

.dockerignore line 7 reads:

node_modules/

In .gitignore, a bare directory pattern like node_modules/ (no leading
or embedded slash) matches that directory name at any depth in the
tree. Docker's .dockerignore parser does not carry over this behavior:
per the Docker build context docs,
a pattern without **/ is anchored and only matches at the root of the
build context. So the current pattern only excludes the top-level
./node_modules, not any node_modules directory that might exist deeper
in the tree (e.g. under scripts/, chart/, or any subpackage added in
the future) — the opposite of what the pattern is clearly meant to do.

Change

Single-line fix in .dockerignore:

# before
node_modules/

# after
**/node_modules/

The **/ prefix is the documented Docker idiom for "match this pattern at
any depth," which restores the intended gitignore-like behavior the file
was already written to assume.

Verification

• Read Docker's official .dockerignore syntax docs to confirm **/ is
  required for depth-independent matching (unlike .gitignore).
• Confirmed via grep/directory listing that the rest of .dockerignore
  and the Dockerfile build context are unaffected by this change — no
  other rule relies on node_modules/ staying root-only.
• No nested node_modules currently exists in this repo (single
  package.json, not a workspace/monorepo), so this change is a no-op for
  the current tree and only guards against future/incidental nested
  node_modules directories inflating the build context or getting
  copied into an image layer.

Note: Claude Code was used to assist in drafting this fix. All changes were reviewed by the submitter.

[RudrenduPaul]

Just flagging for visibility: this is a single-line, narrowly-scoped fix (.dockerignore pattern only) that I've verified against Docker's own documented .dockerignore semantics. Happy to adjust scope, add tests, or close if this isn't a direction you want — let me know either way.