refactor(mcp): drop fable_ prefix from tool names; rebrand to Scribe

MCP clients see tools namespaced by the server's local name already
(mcp__<server>__<tool>), so the fable_ prefix on every tool name was
redundant and ate tokens in the model's tool list.

Tools renamed (34 total):
  fable_search → search
  fable_list_notes / get_note / create_note / update_note / delete_note → list_notes / ...
  fable_list_tasks / get_task / create_task / update_task / add_task_log → list_tasks / ...
  fable_list_projects / get_project / create_project / update_project → list_projects / ...
  fable_list_milestones / create_milestone / update_milestone → list_milestones / ...
  fable_list_events / create_event / get_event / update_event / delete_event → list_events / ...
  fable_list_tags → list_tags
  fable_get_recent → get_recent
  fable_list_persons / create_person / update_person → list_persons / ...
  fable_list_places / create_place / update_place → list_places / ...
  fable_list_lists / create_list / update_list → list_lists / ...

Also rebranded in MCP scope:
  FastMCP("fable", ...) → FastMCP("scribe", ...)
  auth realm "fable-mcp" → "scribe-mcp"
  ASGI scope key fable_user_id → scribe_user_id
  ContextVar label fable_mcp_user_id → scribe_mcp_user_id
  Tool docstrings "in Fable" / "Fable task" → "in Scribe" / "Scribe task"
  Server _INSTRUCTIONS prose

Deliberately kept:
  - The internal Python package name `fabledassistant` (per project naming
    convention — internal stays).
  - "Fabled Scribe" as the official product/brand name (page footer,
    smtp_from_name default).
  - References to the legacy `fable-mcp/` standalone package in docstrings
    explaining what we ported from — accurate until that directory is
    deleted in Phase 10.

Client impact: existing MCP registrations need
  claude mcp remove <name> && claude mcp add ...
once with a freshly-copied snippet from Settings → MCP Access. Claude
Code then re-discovers tools on connect — old conversations that
referenced fable_* tool names will see "tool not found" on those calls
until updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/fabledassistant/mcp/server.py

@@ -5,15 +5,16 @@ from mcp.server.fastmcp import FastMCP
 from quart import Quart
 
 _INSTRUCTIONS = """
-Fabled Scribe is the user's self-hosted second-brain and project-management
-data store. You (Claude) are the assistant.
+Scribe is the user's self-hosted second-brain and project-management data
+store. You (Claude) are the assistant.
 
 Hierarchy: Project -> Milestone -> Task/Note.
 
 - Notes and Tasks share a model; tasks are notes with is_task=True.
-- Use fable_*_note tools for notes, fable_*_task tools for tasks.
-- Typed entities (person, place, list) are notes with a type field plus
-  type-specific columns; use the dedicated tools for those.
+- Use the *_note tools for notes, the *_task tools for tasks. Don't mix them.
+- Typed entities (person, place, list) are notes with a non-default note_type
+  plus type-specific columns; use the dedicated *_person / *_place / *_list
+  tools rather than create_note.
 - Tags are plain strings (no `#` prefix). Empty list clears tags; omit to leave
   unchanged on updates.
 - For optional integer FKs (project_id, milestone_id, parent_id), use 0 to mean
@@ -23,7 +24,7 @@ Hierarchy: Project -> Milestone -> Task/Note.
 
 def build_mcp_server() -> FastMCP:
     """Build the FastMCP instance with all tools registered."""
-    mcp = FastMCP("fable", instructions=_INSTRUCTIONS.strip())
+    mcp = FastMCP("scribe", instructions=_INSTRUCTIONS.strip())
     from fabledassistant.mcp.tools import register_all
     register_all(mcp)
     return mcp
@@ -34,7 +35,7 @@ def mount_mcp(app: Quart) -> None:
 
     A small ASGI middleware between Quart and the FastMCP sub-app validates the
     Bearer token against the api_keys table. Authenticated requests have their
-    user_id attached to the ASGI scope under "fable_user_id" for tool handlers
+    user_id attached to the ASGI scope under "scribe_user_id" for tool handlers
     to read in later phases.
     """
     from fabledassistant.mcp.auth import resolve_bearer_to_user_id
@@ -55,7 +56,7 @@ def mount_mcp(app: Quart) -> None:
                 "status": 401,
                 "headers": [
                     (b"content-type", b"application/json"),
-                    (b"www-authenticate", b'Bearer realm="fable-mcp"'),
+                    (b"www-authenticate", b'Bearer realm="scribe-mcp"'),
                 ],
             })
             await send({
@@ -63,7 +64,7 @@ def mount_mcp(app: Quart) -> None:
                 "body": b'{"error":"unauthorized"}',
             })
             return
-        scope["fable_user_id"] = user_id
+        scope["scribe_user_id"] = user_id
         from fabledassistant.mcp._context import _user_id_ctx
         token = _user_id_ctx.set(user_id)
         try: