Tighten request filtering and fix compose config

[H4mid2019]

Reduce false positives in the request filter and fix docker-compose.

• Replace bare-substring keyword matching (SELECT, cat, echo, etc.) with context-aware regexes so legitimate values like ?category= or /echolocation are no longer blocked.
• Drop redundant path prefix/exact lists now covered by the contains/suffix checks.
• Apply a single command-injection regex to both path and decoded query.
• Add regression tests for legitimate traffic.
• docker-compose: real redis healthcheck and PORT aligned with nginx.conf/README.