docs: VISION for v1.0 + clarify docs/ vs agent/ vs .claude

Add docs/VISION.md (product themes, v1.0 bar, agent slice hints) and
README maps under docs/ and agent/. Point ROADMAP, BACKLOG, LOOP,
CLAUDE, HARDWARE, and the root README at the split: VISION = intent,
BACKLOG = executable queue, ROADMAP = design history, .claude = harness
only. Mark v1.0 track in BACKLOG PROPOSED for human triage.

agent/LOOP.md

@@ -57,7 +57,11 @@ Spend expensive tokens on judgment, not mechanics.
 
 ### 0. Orient
 1. Read `GOALS.md`, `CONVENTIONS.md`, `MEMORY.md`, the **last 3–5 entries**
-   of `JOURNAL.md`, and `BACKLOG.md`.
+   of `JOURNAL.md`, and `BACKLOG.md`. If the top task is product-shaped
+   (UX, release bar, day-2 confidence), also read the matching section of
+   **`docs/VISION.md`** — do not invent work from VISION; only execute
+   BACKLOG items. Map of docs vs agent state: `docs/README.md`,
+   `agent/README.md`.
 2. `git pull --ff-only` (skip silently if offline). Confirm you are on
    `main` with a clean tree. **A dirty tree you didn't create → stop and
    report; never stash or discard someone else's work.**