Fix configuration file parsing bugs and typos

[apoorvdarshan]

Summary

• Fix heap buffer overflow in parse_file() — 128-byte buffer written with no bounds check on long config lines
• Fix broken EOF detection — fgetc() return stored in char instead of int, causing infinite loop on unsigned-char platforms or premature EOF on 0xFF bytes
• Fix missing NULL check after malloc(128) — immediate dereference on allocation failure
• Fix missing null-terminator on accumulated string buffer
• Fix last config line silently dropped if file lacks trailing newline
• Fix typos in configuration_map[]: FIX_PADDINDG → FIX_PADDING, INVASTIGATE_PACKET → INVESTIGATE_PACKET

Test plan

• Build the project and verify no compilation errors
• Create a test ccextractor.cnf with a line longer than 127 chars (should be truncated, not overflow)
• Create a test config file not ending with \n (last line should be parsed)
• Verify corrected key names FIX_PADDING and INVESTIGATE_PACKET are recognized