extropy validate: add persona config validation and improve scenario file routing

[DeveshParagiri]

Problem

extropy validate currently only handles two file types:

1. Population specs (.yaml) → _validate_population_spec()
2. Scenario specs (detected by filename containing "scenario") → _validate_scenario_spec()

Two gaps:

1. No persona config validation

There is no validation path for persona.v*.yaml files. After extropy persona generates a config, there's no way to validate it short of manually reading the YAML.

Persona validation should check:

• All attributes from the population spec + scenario extended attributes have phrasing entries
• Boolean phrasings have both true_phrase and false_phrase
• Categorical phrasings cover all options defined in the population spec
• Relative attributes have all 5 z-score labels (much_below, below, average, above, much_above)
• Concrete attributes have valid format_spec and template with {value} placeholder
• Group assignments are valid (every attribute in a group, no orphans)
• Intro template references only attributes that exist

2. Scenario file routing is fragile

The current routing (_is_scenario_file()) detects scenario files by filename pattern. This should be documented or made more robust. The validator also doesn't clearly distinguish between the new study-folder flow (base_population reference) and the legacy flow (population_spec + study_db paths).

The scenario validator itself is thorough (event, exposure, spread, outcomes, timeline, simulation config, file refs) but the CLI routing to get there could be clearer.

Proposed Solution

• Add _validate_persona_config() with the checks listed above
• Route persona.v*.yaml files to the new validator
• Consider a --type flag to explicitly specify file type instead of relying on filename detection

[RandomOscillations]

Implemented on branch codex/steps1-3-hardening (see PR #124). Keeping this issue open until merge + integration verification completes.

[RandomOscillations]

Closing as fixed. now includes persona config validation and explicit file routing for scenario/persona/population paths in (including merged base+extended attribute resolution for persona checks).