Add storage commands with shared bucket path resolution

[padak]

Summary

Resolves #35

New command namespace kbagent storage for direct Storage API access:

Command	Description
storage buckets	List buckets with sharing/linked info (source project, source bucket)
storage bucket-detail	Resolve Snowflake paths for shared buckets
storage tables	List tables by project/bucket

Key feature: Snowflake path resolution for shared buckets

kbagent --json storage bucket-detail --project slevomat --bucket-id in.c-db

Output:

Bucket: in.c-db
Linked from: Analyticky Tym (#1507)
Snowflake DB: sapi_1507
Snowflake schema: in.c-keboola-ex-db-mysql
Tables: 606

  ads_order    "sapi_1507"."in.c-keboola-ex-db-mysql"."ads_order"

MCP get_buckets strips this info -- agent can't resolve the correct Snowflake database for cross-project shared buckets. This command fills that gap.

Test plan

• Tested on real Slevomat project with shared bucket from Analyticky Tym
• Correctly resolves sapi_1507 instead of sapi_226
• All 1045 tests pass, lint clean
• Context and SKILL.md updated