Phase 7: authored assets (diagrams, code exhibits, client wall, budget)

Phase 7 is mostly authored assets. This commit is the asset half; the
template half is a Builder child issue because this phase must not write
application code.

DoD items satisfied or advanced:

- [x] Eight diagrams present, both themes, readable at 1x and on mobile
      8 SVGs, one byte-identical <style> block across all 8 (one visual
      language by construction). Light and dark resolve from a single file
      via prefers-color-scheme, verified per file in Chrome: 8/8 return two
      distinct palettes. Geometry verified with getBBox(), not estimated:
      0 findings after fixing 74 (text overflow, partial overlap, empty
      text, out-of-viewBox). Mobile type at the 900px minimum is 14.1/12.2px.

- [x] Six code exhibits with a two-sentence rationale each
      212 verbatim lines across five eras, copied with cp/sed from the
      read-only archive. Every rationale is exactly two sentences about why
      the code is good; every exhibit also carries an honest_note, and where
      the code is not good the note says so (the 3,400-line procedural PHP
      script is presented for its operational judgement, not its structure).

- [~] Every image optimised; total page weight budgeted and recorded
      BUDGET.md records measured raw and gzip weights for all 15 served
      files: 63,802 B raw / 13,220 B gzipped. Zero rasters by design. Page
      weight of a real page is not measurable until Phase 2 templates and
      Phase 3 serving exist, and is recorded as open rather than asserted.

- [x] Archive never linked or exposed
      No mount paths or volume names under content/. Provenance recorded as
      "private archive, path withheld".

- [ ] Client wall reads as deliberate  -> needs markup/CSS (Builder)
- [ ] Lighthouse held at >= 95/95      -> needs a served page (Phase 3)

Also: the client wall is authored as data (45 entries, 44 distinct names) with
the 45-vs-46 discrepancy and the Diajio -> Diageo correction recorded
rather than papered over. No commercial marks are enabled: that is a
permission decision for Sam, so availability is recorded and permission is not
implied.

content/assets/logos/clients.yaml

@@ -0,0 +1,125 @@
+# Phase 7.1 — the client wall
+#
+# Decision: a typographic wall, not a logo collage. 45 entries, 44 distinct names, one
+# typeface, one size, an even grid. Nothing is an image, so nothing can fail to
+# load, and no name is more prominent than another.
+#
+# The Simple Icons audit below was performed for Phase 7. Ten marks exist. They
+# are NOT enabled in this file: putting a client's mark on a public portfolio is
+# a permission decision, not a design decision, so `mark: none` for every entry
+# until Sam says otherwise.
+version: 1
+authored: 2026-10-26
+render: typographic
+mark_policy:
+  default: none
+  enable: "ask Sam before enabling any commercial mark; availability is recorded, permission is not implied"
+  icon_set: "Simple Icons (CC0 paths, trademarks remain with their owners)"
+counts:
+  agencies_listed: 22
+  brands_listed: 23
+  entries_listed: 45
+  distinct_names: 44
+  claimed_by_plan: 46
+  note: >
+    The plan says 46 names and 23 agencies. The source list contains 22 agencies
+    and 23 brands, and 'Pearsons' appears in both groups, so the distinct count
+    is 44. No name has been invented to reach 46; the difference is flagged for
+    Sam rather than papered over.
+corrections_applied:
+  - "Diajio -> Diageo (reference/content-map.md: factual correction, do not undo)"
+  - "AutoCAD listed as the product; the mark that exists is Autodesk's"
+client_wall:
+  agencies:
+    - name: "Clemenger"
+      mark: none
+    - name: "Agency Republic"
+      mark: none
+    - name: "Brand Union"
+      mark: none
+    - name: "Jackpot Joy"
+      mark: none
+    - name: "Bryce Ford"
+      mark: none
+    - name: "RMG Connect"
+      mark: none
+    - name: "Sporting Index"
+      mark: none
+    - name: "Adventis Digital"
+      mark: none
+    - name: "Trinity St"
+      mark: none
+    - name: "Inferno"
+      mark: none
+    - name: "SAS Design"
+      mark: none
+    - name: "Ogilvy"
+      mark: none
+    - name: "Wunderman"
+      mark: none
+    - name: "Illumina"
+      mark: none
+    - name: "Barkers"
+      mark: none
+    - name: "Mook"
+      mark: none
+    - name: "Pearsons"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Penguin"
+      mark: none
+    - name: "Draft London"
+      mark: none
+    - name: "Behan Consulting"
+      mark: none
+    - name: "MCM Entertainment"
+      mark: none
+    - name: "Carsales"
+      mark: none
+  brands:
+    - name: "Carlton Draught"
+      mark: none
+    - name: "Diageo"
+      mark: none
+    - name: "KPMG"
+      mark: none
+    - name: "McDonald's"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Accenture"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "BBC National Archive"
+      mark: none
+    - name: "Bank of America"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "War of the Worlds"
+      mark: none
+    - name: "Madonna (Hard Candy)"
+      mark: none
+    - name: "PlayStation"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "HSBC"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "DHL"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Reuters"
+      mark: none
+    - name: "Volvic"
+      mark: none
+    - name: "AutoCAD"
+      mark: none          # available in Simple Icons; not enabled
+      attribution: "Autodesk" if n == "AutoCAD"
+    - name: "Channel 4"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Pearsons"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Shell"
+      mark: none          # available in Simple Icons; not enabled
+    - name: "Stella Artois"
+      mark: none
+    - name: "Baileys Irish Cream"
+      mark: none
+    - name: "Parkgate Homes"
+      mark: none
+    - name: "Carlton Dry"
+      mark: none
+    - name: "Cottees Cordial"
+      mark: none