chore(design-systems): stop teaching one install's kit in product copy

The operator's check: this must be a system for managing design systems, not one
with the FabledSword family built into it.

No LOGIC was coupled — the audit found zero behavioural dependencies. But every
docstring example, every UI placeholder and several comments named this install's
palette, so a stranger creating their first design system was shown
"FabledSword" as the expected shape and `--fs-obsidian` as the expected token.
Examples teach, and these taught the wrong thing.

Placeholders now describe the SHAPE ("Your house style", "--surface-page")
rather than naming one instance's contents, and the token-name placeholder now
says the thing worth saying: name it for its purpose, because `--obsidian` and
`--button-bg` both stop being true the moment the value or the element changes.

Not fixed here, and it is the one real coupling left: DesignView.vue hardcodes
rule 65's button variants and rule 60's type scale as literal arrays, so a
stranger's Design page would display this family's specs. Those arrays exist
because there was no design system to read from — which there now is. They go
when the panel is repointed (#2295), not before.

Scribe's own stylesheet comments ("Moss action-primary per Hybrid") are left
alone: that is the app CONSUMING the family style, which is what dogfooding
looks like, not the tool assuming it.

src/scribe/mcp/tools/rulebooks.py

@@ -45,7 +45,8 @@ async def create_rulebook(title: str, description: str = "") -> dict:
     Two ways a rulebook reaches projects, set by its always_on flag (toggle via
     update_rulebook):
       - always_on = true  -> binds EVERY one of your projects automatically.
-        Use for universal cross-project norms (e.g. "FabledSword family").
+        Use for universal cross-project norms that apply across every
+        project, not just one.
       - always_on = false -> binds only projects that subscribe
         (subscribe_project_to_rulebook). Use for a THEMED body of rules a
         category of projects shares (e.g. a design system that visual apps
@@ -54,7 +55,7 @@ async def create_rulebook(title: str, description: str = "") -> dict:
     to any single project. Project-specific rules go in create_project_rule.
 
     Args:
-        title: Rulebook name (e.g. "FabledSword family").
+        title: Rulebook name.
         description: Optional short description of what this rulebook covers.
     """
     uid = current_user_id()