docs(content): create the content roadmap — Spine, BOM, Backlog

Implements the docs restructure half of the content-track design (the
currency item is code and stays unbuilt). Content stops being unbounded:
the work is now a countable checklist with an end.

content/roadmap.md — new. Three sections, only one of which is ever the
work:
  Spine     Greywater Docks + one dungeon, patron Ghaul the Yoke; the
            cosmology touching ground. Plus what is already canon.
  BOM       ~57 discrete pieces for a complete, playable game, per
            milestone. Numbers, not vibes.
  Backlog   Everything the slice does not need. Not a debt — where ideas
            go to be safe.

Its rule: never author anything that is not in the Bill of Materials.

The BOM carries a Fixed/Variable column — the seven-campaign saga spec's
only ask of this table. ~37 fixed / ~20 variable: a second town costs the
20, not the 57. That is also the exact split v2 generation would need.

content/lore/canon-roadmap.md becomes a pointer (older specs and plans
reference the old path). An items-and-prices table does not belong under
lore/.

docs/roadmap.md — M4..M9 each gain a "Content it consumes →" line into
the BOM.

world-building skill — SKILL.md and evals.json now point at
content/roadmap.md, and the skill is told to respect the BOM rule: ideas
that arrive during authoring go to the Backlog, not into the world.

Build + --check green; generated content/world and content/server are
byte-identical. No Python touched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/skills/world-building/evals/evals.json

@@ -33,13 +33,13 @@
       "id": 3,
       "name": "new-storyline-file",
       "prompt": "Start a new storyline about a roadside cult bleeding travelers to feed one of the Seven: who they are, and a rumor the player might hear. Make it its own file.",
-      "expected_output": "A new content/lore/*.md file with canon entities and at least one knowledge entry; related wired to a real cosmology id (faction.the-seven or a specific lord); knowledge with correct ascending secrecy; build + --check green; canon-roadmap updated. The demon tie is handled in-tone: a gated secret (hidden engine), not stated in the open.",
+      "expected_output": "A new content/lore/*.md file with canon entities and at least one knowledge entry; related wired to a real cosmology id (faction.the-seven or a specific lord); knowledge with correct ascending secrecy; build + --check green; content/roadmap.md updated. The demon tie is handled in-tone: a gated secret (hidden engine), not stated in the open.",
       "assertions": [
         "Authored a new content/lore/*.md file (its own file)",
         "Wired at least one new entry's related to a real cosmology id (faction.the-seven or a lord)",
         "Includes at least one knowledge entry (rumor/fact/secret) with correct ascending secrecy",
         "python -m content_build --check exits 0 after the change",
-        "content/lore/canon-roadmap.md updated to reflect the new content",
+        "content/roadmap.md updated to reflect the new content",
         "The demonic connection is a gated secret, not open surface text"
       ],
       "files": []