feat: Make Discovery accessible from CLI and SDK (#228)

[rstrahan]

Summary

Makes Discovery accessible from CLI (idp-cli discover) and SDK (client.discovery.run()), addressing #228.

IUsage

Usage: idp-cli discover [OPTIONS]

  Discover document class schema from sample document(s)

  Analyzes document(s) using Amazon Bedrock to automatically generate JSON
  Schema definitions for document classes.

  Ground truth files (-g) are auto-matched to documents (-d) by filename stem:
  invoice.pdf matches invoice.json. Unmatched documents run without ground
  truth.

  For --output (-o) in batch mode: if path is a directory, writes one JSON
  file per schema; if path is a file, writes all schemas as a JSON array.

  Examples:

    # Single document   idp-cli discover -d ./invoice.pdf

    # With ground truth (matched by filename stem)   idp-cli discover -d
    ./invoice.pdf -g ./invoice.json

    # Output to file   idp-cli discover -d ./form.pdf -o ./form-schema.json

    # Batch with auto-matched ground truth   idp-cli discover -d ./invoice.pdf
    -d ./w2.pdf -g ./invoice.json -g ./w2.json

    # Batch with output directory   idp-cli discover -d ./invoice.pdf -d
    ./w2.pdf -o ./schemas/

    # Batch with output file (JSON array)   idp-cli discover -d ./invoice.pdf
    -d ./w2.pdf -o ./all-schemas.json

    # Stack mode (saves to config)   idp-cli discover --stack-name my-stack -d
    ./invoice.pdf --config-version v2

Options:
  --stack-name TEXT        CloudFormation stack name (optional — if omitted,
                           runs in local mode without saving to config)
  -d, --document PATH      Path to document file(s). Specify multiple times
                           for batch: -d doc1.pdf -d doc2.pdf  [required]
  -g, --ground-truth PATH  Path to JSON ground truth file(s). Auto-matched to
                           documents by filename stem
  --config-version TEXT    Configuration version to save the discovered schema
                           to (default: active version)
  --region TEXT            AWS region (optional)
  -o, --output PATH        Output path: file (single doc or JSON array for
                           batch) or directory (one file per schema)
  --help                   Show this message and exit.

Changes

New files

• lib/idp_sdk/idp_sdk/models/discovery.py — DiscoveryResult and DiscoveryBatchResult Pydantic models
• lib/idp_sdk/idp_sdk/operations/discovery.py — DiscoveryOperation with run() and run_batch() methods, local and stack-connected modes
• lib/idp_sdk/tests/unit/test_discovery_operations.py — 17 unit tests

Modified files

• lib/idp_common_pkg/idp_common/discovery/classes_discovery.py — Added file_bytes, ground_truth_data, save_to_config optional params (backward compatible)
• lib/idp_sdk/idp_sdk/client.py — Added discovery namespace (10th operation)
• lib/idp_sdk/idp_sdk/operations/__init__.py — Export DiscoveryOperation
• lib/idp_sdk/idp_sdk/models/__init__.py — Export discovery models
• lib/idp_cli_pkg/idp_cli/cli.py — Added discover command with optional --stack-name
• docs/idp-cli.md — Added discover command documentation
• docs/idp-sdk.md — Added discovery operations documentation
• lib/idp_common_pkg/README.md — Added Discovery to core services list
• lib/idp_common_pkg/idp_common/README.md — Added Discovery usage example
• CHANGELOG.md — Added entry under [Unreleased]

Key design decisions

• No S3 uploads — document bytes read locally, passed directly to Bedrock via file_bytes parameter
• --stack-name optional — without it, runs in local mode using system default Bedrock settings from base-discovery.yaml
• Single discover CLI command — -d repeatable for batch mode
• Backward compatible — all new ClassesDiscovery parameters are optional; existing Lambda callers unaffected
• Merged fix/discovery — Discovery no longer injects default config classes into target version

Testing

• 65 SDK unit tests pass (17 new discovery tests)
• 28 idp_common discovery unit tests pass
• All lint checks clean (ruff)

Closes #228