Add compose v5 compatibility, legacy-field warnings, UI error fixes

[SohamKukreti]

Summary

Companion to the self-hosting docs update; all changes verified against a built 0.9.2 image.

docker-compose.yml:

• Express the PID cap as deploy.resources.limits.pids instead of pids_limit: Compose v5 normalizes the two together and rejected the file ("can't set distinct values on 'pids_limit' and 'deploy.resources.limits.pids'"), which also broke compose down. Identical behavior on Compose v2.x.

entrypoint.sh:

• When no CRAWL4AI_API_TOKEN is set, explain that the loopback bind is the container's own (published ports reset connections) and how to fix it. The old one-line notice read as "available at 127.0.0.1:11235" and sent users debugging the wrong thing.

server.py / schemas.py:

• /screenshot and /pdf: output_path (removed in 0.9.0) was silently dropped; requests still succeed but now return a warning that no file was written and results are fetched via GET /artifacts/{artifact_id}.
• Legacy hooks.code (removed in 0.9.0) parsed as an empty hook list and reported {"status": "success", "attached": []} with hooks enabled. The field is now captured (never executed) and the response reports status "ignored" plus a warning; /crawl/stream sends X-Hooks-Warning. With hooks disabled, any hooks payload still returns 403 (unchanged).
• Add "/" to the auth gate's exact-match public paths so the existing root -> /playground redirect is reachable; previously the middleware returned a bare 401 before the route ran. /monitor and all data routes remain gated.

static/playground/index.html:

• The streaming branch never checked response.ok and showed a green "Success" banner for 401 bodies; it now errors before reading the stream. All branches surface the server's detail message instead of a generic "Request failed", and 401s hint at the token bar (distinguishing "no token set" from "token rejected").

tests:

• Add deploy/docker/tests/test_legacy_compat.py covering the root redirect, output_path warning, legacy-hooks handling, and the compose PID-cap placement (13 behavioral tests, TestClient-based).

Fixes #2091

List of files changed and why

• deploy/docker/entrypoint.sh
• deploy/docker/schemas.py
• docker/server.py
• docker/static/playground/index.html
• deploy/docker/tests/test_legacy_compat.py
• docker-compose.yml

How Has This Been Tested?

Ran old tests and also created a new test file to test the changes. Manually verified as well.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes