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.

frontend/src/views/DesignSystemsView.vue

@@ -530,7 +530,7 @@ function isColourish(value: string): boolean {
         <label class="field-label" for="first-title">Title</label>
         <input
           id="first-title" v-model="newTitle" class="input" type="text"
-          placeholder="FabledSword" @keyup.enter="submitCreate"
+          placeholder="Your house style" @keyup.enter="submitCreate"
         />
       </div>
       <div class="field">
@@ -581,7 +581,7 @@ function isColourish(value: string): boolean {
             <label class="field-label" for="new-title">Title</label>
             <input
               id="new-title" v-model="newTitle" class="input" type="text"
-              placeholder="FabledSword, or Scribe" @keyup.enter="submitCreate"
+              placeholder="A house style, or one app in it" @keyup.enter="submitCreate"
             />
           </div>
           <div class="field">
@@ -852,7 +852,7 @@ function isColourish(value: string): boolean {
                 <label class="field-label" for="token-name">Name</label>
                 <input
                   id="token-name" v-model="tokenName" class="input mono" type="text"
-                  placeholder="--fs-obsidian"
+                  placeholder="--surface-page"
                 />
               </div>
               <div class="field-row">
@@ -864,7 +864,7 @@ function isColourish(value: string): boolean {
                   <label class="field-label" for="token-purpose">Purpose</label>
                   <input
                     id="token-purpose" v-model="tokenPurpose" class="input" type="text"
-                    placeholder="page bg, deepest surface"
+                    placeholder="page background, deepest surface"
                   />
                 </div>
               </div>
@@ -873,7 +873,7 @@ function isColourish(value: string): boolean {
                 <label class="field-label" for="token-rationale">Why this value</label>
                 <input
                   id="token-rationale" v-model="tokenRationale" class="input" type="text"
-                  placeholder="Success equals Moss, aligned by design"
+                  placeholder="Matches the primary action colour, deliberately"
                 />
                 <p class="field-hint">
                   Distinct from purpose: purpose is what the token is FOR, this is