docs: record editor-first UI-scene convention (ADR 0001)

Capture the direction change from M3-b: UI screens are authored editor-first
as .tscn node trees (previewable/arrangeable in the Godot editor), scripts do
on-load work only — never build the tree in _ready(). Add ADR 0001, a
"UI scene conventions" how-to in client/docs, a §16 mandate in the charter,
and mark M3-a/M3-b done in the roadmap.

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

docs/roadmap.md

@@ -55,9 +55,9 @@ M0–M2 built the **engine** (the contract, the client, the server loop, bounded
 Each screen is recreated as a Godot 4.7 Control-node scene against the mockups (§16); each `.dc.html`'s `Component` class is the behavior spec. Sequenced toward a playable vertical slice (shell → creation → combat → dialogue) first, then breadth.
 
 ### M3 — Visual foundation & shell ◀ *here*
-- ○ **Shared `Theme`** — palette tokens, the three font families, and reusable styleboxes (parchment card, dark panel, primary CTA, tab, item tile, tag/chip) from the mock README as a Godot `Theme` resource. Every screen pulls from it; build it first so the look is one system. *§2: n/a (presentation) · depends on nothing · goal: one consistent visual identity.*
-- ○ **Main Window shell (2a)** — the exploration HUD: isometric world-view slot + the permanent DM "narration book" (wired to the proven `/dm/narrate` loop + considering-state), the turn-order rail, minimap slot, the slide-in system dock (Inventory/Character/Quest/Map/Party toggles), and the bottom command bar (HP/MP/gold, consumables, End Turn). The frame everything else lives in. *§2: state (client owns the HUD, consumes DM text) · depends on the DM loop (M2) · goal: the game's main screen, on screen.*
-- ○ **Title screen** — new game / continue / load / settings; the entry point. *§2: n/a · depends on the Theme · goal: first impression, into the world.*
+- ✅ **Shared `Theme`** — palette tokens, the three font families, and reusable styleboxes (parchment card, dark panel, primary CTA, tab, item tile, tag/chip) from the mock README as a Godot `Theme` resource. Every screen pulls from it; build it first so the look is one system. Merged to `dev`. *§2: n/a (presentation) · depends on nothing · goal: one consistent visual identity.*
+- ✅ **Main Window shell (2a)** — the exploration HUD: isometric world-view slot + the permanent DM "narration book" (wired to the proven `/dm/narrate` loop + considering-state), the turn-order rail, minimap slot, the slide-in system dock (Inventory/Character/Quest/Map/Party/Spellbook toggles), and the bottom command bar (HP/MP/gold, consumables, End Turn). The frame everything else lives in. **Established the editor-first UI-scene convention** (ADR [0001](adr/0001-editor-first-ui-scenes.md); how-to in `client/docs/README.md`) and added Button-base `DockButton`/`ParchmentButton` + a base `RichTextLabel` prose style to the theme. *§2: state (client owns the HUD, consumes DM text) · depends on the DM loop (M2) · goal: the game's main screen, on screen.*
+- ○ **Title screen** — new game / continue / load / settings; the entry point. Author it editor-first (ADR 0001). *§2: n/a · depends on the Theme · goal: first impression, into the world.*
 
 ### M4 — Character creation
 - ○ **Character creation UI** — the mock's screen over our proven model: race + calling cards, six stats with **LCK hidden entirely** (§7), 3d6 floors, the **+3 additive-only spend-up** pool (§8, matches the `character-creation-stats` model), live origin blurb + nameplate. **Reconcile class names** here (§8 vs the mock's callings). Feeds new-game canon-log construction (already built). *§2: state · depends on the creation model (M0) + Theme · goal: build a character.*