feat(scraper): add regex-based pattern matching for node selection

[theonlychant]

Summary

Adds regex-based pattern matching for node selection, allowing more
flexible and powerful scraping patterns beyond exact string matches.

Test plan

• pytest test/unit
• pytest test/functional (if applicable)
• pre-commit run --all-files

Checklist

• Added/updated tests :: added unit tests covering regex pattern matching,
  invalid patterns, and edge cases
• Updated docs/README to document the new regex selector syntax
• No secrets or credentials committed

[alexandraBara]

This functionality can be achieved today without enhancing the code:

from nodescraper.plugins.regex_search.analyzer_args import RegexSearchAnalyzerArgs
from nodescraper.plugins.regex_search.regex_search_analyzer import RegexSearchAnalyzer
from nodescraper.plugins.regex_search.regex_search_data import RegexSearchData
# Inline the same patterns you would have taken from COMMON_PATTERNS
rules = [
    {
        "regex": r"\b(?:25[0-5]|2[0-4]\d|1?\d?\d)(?:\.(?:25[0-5]|2[0-4]\d|1?\d?\d)){3}\b",
        "message": "Found ipv4",
        "event_category": "UNKNOWN",
        "event_priority": "ERROR",
    },
    {
        "regex": r"\b[\w.+-]+@[\w-]+(?:\.[\w-])+\b",
        "message": "Found email",
        "event_category": "UNKNOWN",
        "event_priority": "ERROR",
    },
]
data = RegexSearchData(content="2026-05-01T12:00:00,000+00:00 connect from 192.0.2.1")
analyzer = RegexSearchAnalyzer(system_info=system_info) 
result = analyzer.analyze_data(data, RegexSearchAnalyzerArgs(error_regex=rules))

Same can be achieved today without code enhancements by using this sample plugin_config.json:

{
  "global_args": {},
  "plugins": {
    "RegexSearchPlugin": {
      "collection": false,
      "analysis": true,
      "data": "/path/to/your.log",
      "analysis_args": {
        "interval_to_collapse_event": 60,
        "num_timestamps": 3,
        "error_regex": [
          {
            "regex": "\\b(?:25[0-5]|2[0-4]\\d|1?\\d?\\d)(?:\\.(?:25[0-5]|2[0-4]\\d|1?\\d?\\d)){3}\\b",
            "message": "IPv4 address matched",
            "event_category": "UNKNOWN",
            "event_priority": "ERROR"
          },
          {
            "regex": "\\b(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}\\b",
            "message": "MAC address matched",
            "event_category": "NETWORK",
            "event_priority": "WARNING"
          }
        ]
      }
    }
  },
  "result_collators": {},
  "name": "regex search with ipv4 + mac (COMMON_PATTERNS strings inlined)",
  "desc": "Regex strings copied from nodescraper.regex_patterns COMMON_PATTERNS"
}

Which you can run like:

node-scraper --plugin-config plugin_config.json