refactor(mcp): one rules_payload() for every surface that hands rules to an agent; drop the dead bearer resolver (#2828, milestone 296 area 4)

Reading the 16 tool modules against each other: the six-key applicable-rules
block (applicable_rules, applicable_rules_truncated, subscribed_rulebooks,
project_rules, suppressed_rules, suppressed_topics) was hand-built in five
places — enter_project, get_project, get_task (legacy plans), get_milestone
(three of the six) and services/planning.start_planning. rulebooks_svc.
rules_payload() is now the one place that names them; get_milestone gains the
three it lacked, so every rules-carrying payload reads the same. list_rules /
list_always_on_rules share _rule_summary. mcp/auth.resolve_bearer_to_user_id
duplicated resolve_bearer's parsing and had no product caller (only its own
tests) — removed; the tests now exercise resolve_bearer.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/mcp/tools/projects.py

@@ -192,12 +192,7 @@ async def enter_project(project_id: int) -> dict:
         ],
         "design_system": design_system,
         "milestone_summary": milestone_summary,
-        "applicable_rules": applicable["rules"],
-        "project_rules": applicable.get("project_rules", []),
-        "suppressed_rules": applicable.get("suppressed_rules", []),
-        "suppressed_topics": applicable.get("suppressed_topics", []),
-        "subscribed_rulebooks": applicable["subscribed_rulebooks"],
-        "applicable_rules_truncated": applicable["truncated"],
+        **rulebooks_svc.rules_payload(applicable),
         "open_tasks": [
             {
                 "id": t.id, "title": t.title, "status": t.status,
@@ -239,12 +234,7 @@ async def get_project(project_id: int) -> dict:
     applicable = await rulebooks_svc.get_applicable_rules(
         project_id=project_id, user_id=uid,
     )
-    data["applicable_rules"] = applicable["rules"]
-    data["applicable_rules_truncated"] = applicable["truncated"]
-    data["subscribed_rulebooks"] = applicable["subscribed_rulebooks"]
-    data["project_rules"] = applicable.get("project_rules", [])
-    data["suppressed_rules"] = applicable.get("suppressed_rules", [])
-    data["suppressed_topics"] = applicable.get("suppressed_topics", [])
+    data.update(rulebooks_svc.rules_payload(applicable))
     return data