fix: set up log formatting to human readable text and set that as the default

[ktstrader]

Description

OpenHound previously wrote all file/stdout logs as JSON, which is hard to read when tailing logs or debugging locally. So this introduces human-readable plain-text log format and makes it the default, while keeping structured JSON available as an opt-in.

Changes:

• New OpenHoundTextFormatter — renders each record as a single readable line:
  2026-06-25 12:00:00 [INFO] logger:function:line - message | key=value
• Extra/structured fields (e.g. resource, phase, extension) are appended as key=value pairs so context is preserved without full JSON. Null extras (like taskName) are dropped, and exceptions are appended on a following line.
• Format selection — added log_format (default "text"), a _validate_format() helper, and a _file_formatter() method that returns the JSON or text formatter based on config. All three handler modes (container, CLI, service) now use _file_formatter() instead of hardcoding JSON.
• Config toggle via dlt's reserved key — the format is read from runtime.log_format. dlt treats only the exact string "JSON" specially (and skips format-string validation for it), so we piggyback on that: "JSON" selects JSON logs; anything else (including dlt's default format string when unset) falls back to text. This avoids introducing a separate namespace and avoids the ValueError: invalid format crash that other values trigger.
• Example configs — removed the hardcoded log_format = "JSON" from both BloodHound Community and Enterprise example configs; documented text as the default with a commented, uppercase # log_format = "JSON" opt-in.

Tests:

• test_validate_format_defaults_to_text — validates "JSON"/"text" and the text fallback for invalid values.
• test_file_formatter_selection — confirms log_format selects the matching formatter.
• test_text_formatter_produces_plain_text — asserts the text output renders the message/args, level, location, and extras, and is not valid JSON.
• test_log_routing_content — pins RUNTIME__LOG_FORMAT=JSON so its JSON-parsing assertions stay self-contained regardless of the new default.

Motivation and Context

Resolves: BED-8744

Screenshots

Default:

2026-06-25 11:48:13 [INFO] openhound.core.manager:validate_metadata:119 - Extension 'faker' has valid metadata | extension=faker phase=metadata_validation
2026-06-25 11:48:13 [INFO] openhound.core.manager:from_entrypoint:156 - Loaded extension 'faker' from entry point 'openhound.sources' | extension=faker phase=extension_loading
2026-06-25 11:48:13 [INFO] openhound.core.manager:validate_metadata:119 - Extension 'github' has valid metadata | extension=github phase=metadata_validation
2026-06-25 11:48:13 [INFO] openhound.core.manager:from_entrypoint:156 - Loaded extension 'github' from entry point 'openhound.sources' | extension=github phase=extension_loading
2026-06-25 11:48:13 [INFO] openhound.core.manager:validate_metadata:119 - Extension 'jamf' has valid metadata | extension=jamf phase=metadata_validation
2026-06-25 11:48:13 [INFO] openhound.core.manager:from_entrypoint:156 - Loaded extension 'jamf' from entry point 'openhound.sources' | extension=jamf phase=extension_loading
2026-06-25 11:48:13 [INFO] openhound.core.collect:run:61 - Starting collector 'jamf'
2026-06-25 11:48:14 [ERROR] openhound.core.resources:sync_wrapper:68 - Error in resource 'users' during iteration: Expecting value: line 1 column 1 (char 0) | resource=users phase=resource_iteration

With log_format = "JSON" set in config.toml:

{"timestamp": "2026-06-25 11:46:12", "level": "INFO", "logger": "openhound.core.manager", "module": "manager", "function": "validate_metadata", "line": 119, "message": "Extension 'faker' has valid metadata", "openhound_version": "0.2.9.dev1", "taskName": null, "extension": "faker", "phase": "metadata_validation"}
{"timestamp": "2026-06-25 11:46:12", "level": "INFO", "logger": "openhound.core.manager", "module": "manager", "function": "from_entrypoint", "line": 156, "message": "Loaded extension 'faker' from entry point 'openhound.sources'", "openhound_version": "0.2.9.dev1", "taskName": null, "extension": "faker", "phase": "extension_loading"}
{"timestamp": "2026-06-25 11:46:12", "level": "INFO", "logger": "openhound.core.manager", "module": "manager", "function": "validate_metadata", "line": 119, "message": "Extension 'github' has valid metadata", "openhound_version": "0.2.9.dev1", "taskName": null, "extension": "github", "phase": "metadata_validation"}