[TW-4826] feat(scheduler): add extended flags, file input, and validation to configurations

[qasim-nylas]

Summary

Enhances nylas scheduler configurations create and update commands with full Nylas Scheduler API coverage, JSON file input support, and fail-fast validation.

• Add 16 new flags covering availability settings, event booking options, scheduler settings, and --file JSON input with flag-override support
• Extract helpers to configurations_helpers.go for flag registration, enum validation, request building, and display formatting
• Move validation before auth so users get immediate feedback on missing/invalid fields without needing API credentials

Details

New Flags

Category	Flags
Availability	--interval, --round-to, --availability-method, --buffer-before, --buffer-after
Event Booking	--timezone, --booking-type, --conferencing-provider, --disable-emails, --reminder-minutes
Scheduler Settings	--min-booking-notice, --min-cancellation-notice, --confirmation-method, --available-days-in-future, --cancellation-policy
File Input	--file (JSON config file; flags override file values)

File Input Support

Users can now create/update configurations from a JSON file matching the API request structure. When both --file and flags are provided, flags take precedence over file values. This enables workflows like:

# Export → edit → recreate
nylas scheduler configs show abc123 --json > meeting.json
# Edit meeting.json...
nylas scheduler configs create --file meeting.json

# File as base, override specific values
nylas scheduler configs create --file config.json --duration 60

Refactoring

• configurations_helpers.go (new) — Extracted configFlags struct, registerConfigFlags(), validateConfigFlags(), buildCreateRequest(), buildUpdateRequest(), and formatConfigDetails() from inline code in configurations.go
• Fail-fast validation — validateConfigFlags() checks enum values and validateCreateRequest()/validateUpdateRequest() check required fields before WithClient() is called, so errors like missing --name or invalid --booking-type surface without requiring auth
• Removed MarkFlagRequired — Replaced with custom validation to support the --file input path where fields come from the file rather than flags

Files Changed

File	Change
internal/cli/scheduler/configurations.go	Refactored create/update commands to use extracted helpers and new flags
internal/cli/scheduler/configurations_helpers.go	New — Flag registration, validation, request building, display formatting
internal/cli/scheduler/configurations_helpers_test.go	New — Unit tests for all helper functions (validation, request building, file input, display)
internal/cli/scheduler/configurations_command_test.go	New — Command-level tests verifying validation errors occur before auth errors
internal/cli/scheduler/scheduler_test.go	Expanded flag existence tests for new availability, event booking, scheduler, and file flags
docs/commands/scheduler.md	Updated with flags table, examples, and file input documentation

Test Plan

• Unit tests for enum validation (validateConfigFlags) — valid and invalid values for all enum flags
• Unit tests for buildCreateRequest — file-only, flags-only, flags-override-file scenarios
• Unit tests for buildUpdateRequest — file-only, flags-only, flags-override-file scenarios
• Unit tests for validateCreateRequest / validateUpdateRequest — missing fields, empty update detection
• Unit tests for formatConfigDetails — full config and minimal config output
• Command-level tests confirming validation errors fire before auth errors (no API key needed)
• Flag existence tests for all 16 new flags on both create and update commands
• Manual: nylas scheduler configs create --name "Test" --title "Test" --participants user@example.com --duration 30
• Manual: nylas scheduler configs create --file config.json
• Manual: nylas scheduler configs update <id> --buffer-before 5 --conferencing-provider "Google Meet"

JIRA: TW-4826

[AaronDDM]

LGTM 👍