feat: workspace-based multi-tenancy, replacing user as tenancy axis (#840)

Introduces `workspace` as the isolation boundary for config, flows,
library, and knowledge data. Removes `user` as a schema-level field
throughout the code, API specs, and tests; workspace provides the
same separation more cleanly at the trusted flow.workspace layer
rather than through client-supplied message fields.

Design
------
- IAM tech spec (docs/tech-specs/iam.md) documents current state,
  proposed auth/access model, and migration direction.
- Data ownership model (docs/tech-specs/data-ownership-model.md)
  captures the workspace/collection/flow hierarchy.

Schema + messaging
------------------
- Drop `user` field from AgentRequest/Step, GraphRagQuery,
  DocumentRagQuery, Triples/Graph/Document/Row EmbeddingsRequest,
  Sparql/Rows/Structured QueryRequest, ToolServiceRequest.
- Keep collection/workspace routing via flow.workspace at the
  service layer.
- Translators updated to not serialise/deserialise user.

API specs
---------
- OpenAPI schemas and path examples cleaned of user fields.
- Websocket async-api messages updated.
- Removed the unused parameters/User.yaml.

Services + base
---------------
- Librarian, collection manager, knowledge, config: all operations
  scoped by workspace. Config client API takes workspace as first
  positional arg.
- `flow.workspace` set at flow start time by the infrastructure;
  no longer pass-through from clients.
- Tool service drops user-personalisation passthrough.

CLI + SDK
---------
- tg-init-workspace and workspace-aware import/export.
- All tg-* commands drop user args; accept --workspace.
- Python API/SDK (flow, socket_client, async_*, explainability,
  library) drop user kwargs from every method signature.

MCP server
----------
- All tool endpoints drop user parameters; socket_manager no longer
  keyed per user.

Flow service
------------
- Closure-based topic cleanup on flow stop: only delete topics
  whose blueprint template was parameterised AND no remaining
  live flow (across all workspaces) still resolves to that topic.
  Three scopes fall out naturally from template analysis:
    * {id} -> per-flow, deleted on stop
    * {blueprint} -> per-blueprint, kept while any flow of the
      same blueprint exists
    * {workspace} -> per-workspace, kept while any flow in the
      workspace exists
    * literal -> global, never deleted (e.g. tg.request.librarian)
  Fixes a bug where stopping a flow silently destroyed the global
  librarian exchange, wedging all library operations until manual
  restart.

RabbitMQ backend
----------------
- heartbeat=60, blocked_connection_timeout=300. Catches silently
  dead connections (broker restart, orphaned channels, network
  partitions) within ~2 heartbeat windows, so the consumer
  reconnects and re-binds its queue rather than sitting forever
  on a zombie connection.

Tests
-----
- Full test refresh: unit, integration, contract, provenance.
- Dropped user-field assertions and constructor kwargs across
  ~100 test files.
- Renamed user-collection isolation tests to workspace-collection.

trustgraph-cli/trustgraph/cli/show_flow_blueprints.py

@@ -11,6 +11,7 @@ import json
 
 default_url = os.getenv("TRUSTGRAPH_URL", 'http://localhost:8088/')
 default_token = os.getenv("TRUSTGRAPH_TOKEN", None)
+default_workspace = os.getenv("TRUSTGRAPH_WORKSPACE", "default")
 
 def format_parameters(params_metadata, param_type_defs):
     """
@@ -44,12 +45,13 @@ def format_parameters(params_metadata, param_type_defs):
 
     return "\n".join(param_list)
 
-async def fetch_data(client):
+async def fetch_data(client, workspace):
     """Fetch all data needed for show_flow_blueprints concurrently."""
 
     # Round 1: list blueprints
     resp = await client._send_request("flow", None, {
         "operation": "list-blueprints",
+        "workspace": workspace,
     })
     blueprint_names = resp.get("blueprint-names", [])
 
@@ -60,6 +62,7 @@ async def fetch_data(client):
     blueprint_tasks = [
         client._send_request("flow", None, {
             "operation": "get-blueprint",
+            "workspace": workspace,
             "blueprint-name": name,
         })
         for name in blueprint_names
@@ -84,6 +87,7 @@ async def fetch_data(client):
         param_type_tasks = [
             client._send_request("config", None, {
                 "operation": "get",
+                "workspace": workspace,
                 "keys": [{"type": "parameter-type", "key": pt}],
             })
             for pt in param_types_needed
@@ -100,14 +104,16 @@ async def fetch_data(client):
 
     return blueprint_names, blueprints, param_type_defs
 
-async def _show_flow_blueprints_async(url, token=None):
+async def _show_flow_blueprints_async(url, token=None, workspace="default"):
     async with AsyncSocketClient(url, timeout=60, token=token) as client:
-        return await fetch_data(client)
+        return await fetch_data(client, workspace)
 
-def show_flow_blueprints(url, token=None):
+def show_flow_blueprints(url, token=None, workspace="default"):
 
     blueprint_names, blueprints, param_type_defs = asyncio.run(
-        _show_flow_blueprints_async(url, token=token)
+        _show_flow_blueprints_async(
+            url, token=token, workspace=workspace,
+        )
     )
 
     if not blueprint_names:
@@ -156,6 +162,12 @@ def main():
         help='Authentication token (default: $TRUSTGRAPH_TOKEN)',
     )
 
+    parser.add_argument(
+        '-w', '--workspace',
+        default=default_workspace,
+        help=f'Workspace (default: {default_workspace})',
+    )
+
     args = parser.parse_args()
 
     try:
@@ -163,6 +175,7 @@ def main():
         show_flow_blueprints(
             url=args.api_url,
             token=args.token,
+            workspace=args.workspace,
         )
 
     except Exception as e: