feat: add blockchain RPC blocks-range endpoint and marketplace bid listing

Blockchain Node:
- Replace /blocks (pagination) with /blocks-range (height range query)
- Add start/end height parameters with 1000-block max range validation
- Return blocks in ascending height order instead of descending
- Update metrics names (rpc_get_blocks_range_*)
- Remove total count from response (return start/end/count instead)

Coordinator API:
- Add effective_url property to DatabaseConfig (SQLite/PostgreSQL defaults

cli/aitbc_cli/main.py

@@ -21,6 +21,7 @@ from .commands.admin import admin
 from .commands.config import config
 from .commands.monitor import monitor
 from .commands.governance import governance
+from .commands.exchange import exchange
 from .plugins import plugin, load_plugins
 
 
@@ -98,6 +99,7 @@ cli.add_command(admin)
 cli.add_command(config)
 cli.add_command(monitor)
 cli.add_command(governance)
+cli.add_command(exchange)
 cli.add_command(plugin)
 load_plugins(cli)