docs(dockerfile): warn about the npm omit=dev + tsc build trap in TypeScript Actors

[DaveHanns]

Summary

Adds a :::warning on source_code.md about the npm install --omit=dev + tsc build trap: --omit=dev drops typescript, so any TS Actor whose build invokes tsc fails at image-build time with sh: tsc: not found. Callout links to the ts-empty template's Dockerfile as the canonical multi-stage reference.

Related — coordinated remediation stack

Four defense layers, each covering a different failure mode:

• apify/actor-templates — ts-* Dockerfiles ship a multi-stage build (already in master via #592, Dec 2025). Users of apify create -t ts-* cannot hit the trap.
• apify/apify-cli#1252 — apify push preflight warning when a Dockerfile has --omit=dev before npm run build that invokes tsc.
• apify/apify-cli#1261 — apify create forces --include=dev + NODE_ENV=development on the post-scaffold install, so apify run works locally.
• This PR — docs callout on the Source-code page for the direct-docker build / search-fallback case.

---

Surfaced during an evaluation of Apify surfaces for agent-driven Actor development.

[apify-service-account]

❌ Preview build for this PR (commit 0a89687c) failed. See action run for details.

[TC-MO]

This should fix the build, I'll tackle the admonition itself separately

[TC-MO]

Suggested change

	- **Multi-stage build** (smallest runtime image)—installs devDeps in a builder stage, copies the compiled output into a slim runtime stage. Most complex Dockerfile.
	<details><summary>Example</summary>
	```dockerfile
	FROM apify/actor-node:24 AS builder
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install --include=dev
	COPY --chown=myuser:myuser . ./
	RUN npm run build
	FROM apify/actor-node:24
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install --omit=dev --omit=optional
	COPY --from=builder --chown=myuser:myuser /usr/src/app/dist ./dist
	CMD ["node", "dist/main.js"]
	```
	</details>
	- **Multi-stage build** (smallest runtime image)—installs devDeps in a builder stage, copies the compiled output into a slim runtime stage. Most complex Dockerfile.
	<details>
	<summary>Example</summary>
	```dockerfile
	FROM apify/actor-node:24 AS builder
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install --include=dev
	COPY --chown=myuser:myuser . ./
	RUN npm run build
	FROM apify/actor-node:24
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install --omit=dev --omit=optional
	COPY --from=builder --chown=myuser:myuser /usr/src/app/dist ./dist
	CMD ["node", "dist/main.js"]

```

[TC-MO]

Suggested change

	- **Drop `--omit=dev`** (simplest Dockerfile, largest runtime image)—installs everything, including linters and type declarations, into the single-stage image.
	<details><summary>Example</summary>
	```dockerfile
	FROM apify/actor-node:24
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install
	COPY --chown=myuser:myuser . ./
	RUN npm run build
	CMD ["node", "dist/main.js"]
	```
	</details>
	- **Drop `--omit=dev`** (simplest Dockerfile, largest runtime image)—installs everything, including linters and type declarations, into the single-stage image.
	<details>
	<summary>Example</summary>
	```dockerfile
	FROM apify/actor-node:24
	COPY --chown=myuser:myuser package*.json ./
	RUN npm install
	COPY --chown=myuser:myuser . ./
	RUN npm run build
	CMD ["node", "dist/main.js"]

```

[TC-MO]

Suggested change

	- **Move `typescript` to `dependencies`**—keeps the single-stage Dockerfile but bloats the runtime image with the TypeScript compiler and its tooling. Runtime never uses these, so the extra size is wasted.
	<details><summary>Example</summary>
	```json
	{
	"dependencies": {
	"apify": "^3.4.0",
	"typescript": "^5.5.0"
	}
	}
	```
	</details>
	- **Move `typescript` to `dependencies`**—keeps the single-stage Dockerfile but bloats the runtime image with the TypeScript compiler and its tooling. Runtime never uses these, so the extra size is wasted.
	<details>
	<summary>Example</summary>
	```json
	{
	"dependencies": {
	"apify": "^3.4.0",
	"typescript": "^5.5.0"
	}
	}

```