Slice 1: scaffolding + propose-to-super-draft vertical

Brings the §1 bot wrapper, the §4 cache (webhook + reconciler), the
§5 schema (six numbered migrations), Gitea OAuth + §6 user
provisioning, the §7 catalog left pane, and the propose-to-merge
vertical: propose modal opens an idea PR against the meta repo, an
owner merges from the pending-idea view, the cache picks it up via
webhook or reconciler sweep, and the catalog renders the new
super-draft.

Per §1 the bot is the only Git writer; every commit, branch
creation, and PR merge carries the §6.5 On-behalf-of: trailer and
an `actions` audit row. Per §4 the cache is never written from a
user action — it's webhook+reconciler only.

Covered by `backend/tests/test_propose_vertical.py` against an
in-process Gitea simulator.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/entry.py

@@ -0,0 +1,102 @@
+"""Meta-repo entry file shape per §2.1.
+
+One markdown file per RFC under rfcs/<slug>.md, frontmatter on top, body
+below. The frontmatter carries the canonical RFC state — id, repo,
+owners, arbiters, graduation timestamps — and the body holds the pitch
+(for super-drafts) or is empty (for graduated entries per §13.3 step 3).
+
+This module contains the parser, the serializer, and a small validator
+for the frontmatter shape. The parser is intentionally lenient about
+unknown keys — future fields land in frontmatter without breaking older
+readers.
+"""
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass, field
+from datetime import date
+from typing import Any
+
+import yaml
+
+FRONTMATTER_RE = re.compile(r"^---\n(.*?)\n---\n?(.*)$", re.DOTALL)
+
+SLUG_RE = re.compile(r"^[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$")
+
+
+@dataclass
+class Entry:
+    slug: str
+    title: str
+    state: str = "super-draft"  # super-draft | active | withdrawn
+    id: str | None = None       # 'RFC-NNNN' or None
+    repo: str | None = None
+    proposed_by: str = ""
+    proposed_at: str = ""        # ISO date
+    graduated_at: str | None = None
+    graduated_by: str | None = None
+    owners: list[str] = field(default_factory=list)
+    arbiters: list[str] = field(default_factory=list)
+    tags: list[str] = field(default_factory=list)
+    body: str = ""
+
+
+def parse(text: str) -> Entry:
+    match = FRONTMATTER_RE.match(text)
+    if not match:
+        raise ValueError("Entry file missing frontmatter")
+    fm = yaml.safe_load(match.group(1)) or {}
+    body = match.group(2).lstrip("\n")
+    return Entry(
+        slug=str(fm.get("slug") or ""),
+        title=str(fm.get("title") or ""),
+        state=str(fm.get("state") or "super-draft"),
+        id=fm.get("id") or None,
+        repo=fm.get("repo") or None,
+        proposed_by=str(fm.get("proposed_by") or ""),
+        proposed_at=str(fm.get("proposed_at") or ""),
+        graduated_at=fm.get("graduated_at"),
+        graduated_by=fm.get("graduated_by"),
+        owners=list(fm.get("owners") or []),
+        arbiters=list(fm.get("arbiters") or []),
+        tags=list(fm.get("tags") or []),
+        body=body,
+    )
+
+
+def serialize(entry: Entry) -> str:
+    """Emit canonical entry file text — frontmatter then body."""
+    fm: dict[str, Any] = {
+        "slug": entry.slug,
+        "title": entry.title,
+        "state": entry.state,
+        "id": entry.id,
+        "repo": entry.repo,
+        "proposed_by": entry.proposed_by,
+        "proposed_at": entry.proposed_at,
+        "graduated_at": entry.graduated_at,
+        "graduated_by": entry.graduated_by,
+        "owners": entry.owners,
+        "arbiters": entry.arbiters,
+        "tags": entry.tags,
+    }
+    yaml_text = yaml.safe_dump(fm, sort_keys=False, default_flow_style=False).rstrip()
+    body = entry.body.lstrip("\n")
+    if body:
+        return f"---\n{yaml_text}\n---\n\n{body}\n"
+    return f"---\n{yaml_text}\n---\n"
+
+
+def slugify(title: str) -> str:
+    """Deterministic kebab-case per §9.1."""
+    s = title.lower().strip()
+    s = re.sub(r"[^a-z0-9]+", "-", s)
+    return s.strip("-")
+
+
+def today() -> str:
+    return date.today().isoformat()
+
+
+def is_valid_slug(slug: str) -> bool:
+    return bool(SLUG_RE.match(slug)) and len(slug) <= 80