docs(6210): acceptance sweep — src, scripts and frontend leftovers described in the present tense

The acceptance greps found what the per-area passes missed:

- src/scribe: "Phase 7/8" removal notes in projects, settings and
  user_profile; a paragraph promising an auto-summary side effect that no
  longer exists; user_profile's claim that "upcoming MCP profile tools" read
  the profile, which nothing does; an instance count and instance rule
  titles in plugin_context; "MILESTONE 323 DECIDED" in rulebooks.
- scripts/: check_plugin's header and inline comments were a history of
  the incidents behind each guard, with issue numbers in two failure
  messages; check_dangling_styles named this app's classes as its examples;
  check_design_tokens, measure_duplication and mint_plugin_version cited
  issues and checklists.
- frontend/src: forty-odd comments with four-digit issue numbers that the
  earlier frontend scan filtered out as hex colours, plus "used to" and
  "Phase N" notes.

Kept: illustrative ids (`#4181` as a bare-id example, `PR #198`), migration
Create Date headers and one migration's dated data floor, and the plugin
skills' worked examples of how to cite a record.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/utils/deadWeight.ts

@@ -7,11 +7,10 @@
  * position more often has a trigger that fires on the wrong work. Telling an
  * operator to delete one of those would be the wrong nudge about half the time.
  *
- * The table lives here because the copy was about to exist in five places.
- * Three already had their own: `SnippetListView`, `RuleListPane`, and
- * `LessonDetailView` with the sentence inline in its template. The unified
- * Knowledge browse renders notes, tasks, processes, snippets and lessons in one
- * mixed feed (#4230), so it needs all of them at once — and a per-view constant
+ * The table lives here because several surfaces need it: `SnippetListView`,
+ * `RuleListPane`, `LessonDetailView`, and the unified Knowledge browse, which
+ * renders notes, tasks, processes, snippets and lessons in one mixed feed and
+ * so needs all of them at once — and a per-view constant
  * is how three surfaces end up giving three different answers to the same
  * question.
  *

frontend/src/utils/designValues.ts

@@ -1,12 +1,11 @@
 /**
  * Turning a design system's RECORDED values into ones you can look at.
  *
- * Replaces `designTokens.ts` and `designDrift.ts`, which between them read the
- * running app's own stylesheet — names out of a bundled `theme.css`, values out
- * of `getComputedStyle(document.documentElement)`. That could only ever describe
- * the install serving the page, and the design surface is for the projects an
- * install TRACKS (#274). What is left here works on any system's record,
- * including one for an app this browser has never loaded.
+ * Reading the running app's own stylesheet — names out of a bundled
+ * `theme.css`, values out of `getComputedStyle(document.documentElement)` —
+ * could only describe the install serving the page, and the design surface is
+ * for the projects an install TRACKS. Everything here works on any system's
+ * record, including one for an app this browser has never loaded.
  *
  * Nothing in this module reads the document's own tokens or mutates the page.
  */