Release 0.2.0: graduation merge race fix + VITE_APP_NAME + versioning infrastructure

- Fix §13.3 step 4 race against Gitea's async mergeability
  computation: gitea.wait_for_mergeable polls the mergeable
  field before calling merge, and bot._merge_with_retry rides
  out the transient 'Please try again later' response.
- Frontend now requires VITE_APP_NAME at build time
  (frontend/vite.config.js fails the build if unset). Header
  brand, landing H1, and browser title read the deployment's
  configured name.
- Establish framework versioning: VERSION (canonical) +
  frontend/package.json#version mirror; CHANGELOG.md as the
  release log with RFC 2119 / 8174 normative-language
  upgrade-steps; SPEC.md §20 as the binding policy; CLAUDE.md
  capturing the separation-of-concerns rule; docs/DEPLOYMENTS.md
  as the downstream operating manual; docs/QUICKSTART-VISION.md
  staking the future one-command-deploy capability.
- Surgical fix to SPEC.md opening so the spec no longer asserts
  OHM is the corpus the framework produces.
- SPEC.md §19.2 gains the 'Deployment-supplied subject framing'
  candidate that drives the 0.3.0 release.

backend/app/bot.py

@@ -22,11 +22,67 @@ anywhere.
 """
 from __future__ import annotations
 
+import asyncio
 import json
+import logging
 from dataclasses import dataclass
 
 from . import db, notify
-from .gitea import Gitea
+from .gitea import Gitea, GiteaError
+
+log = logging.getLogger(__name__)
+
+
+_MERGE_TRANSIENT_HINTS = (
+    "please try again later",
+    "is not ready",
+    "not ready to be merged",
+)
+
+
+async def _merge_with_retry(
+    gitea: Gitea,
+    org: str,
+    meta_repo: str,
+    pr_number: int,
+    *,
+    merge_message_title: str,
+    merge_message_body: str,
+    attempts: int = 3,
+    delay_seconds: float = 1.0,
+) -> None:
+    """Call gitea.merge_pull and retry on Gitea's transient
+    "Please try again later" / "not ready" responses. After
+    `wait_for_mergeable` returns this is rare, but Gitea has been
+    observed to flip back to the unready state momentarily on a
+    write-amplified instance; a small bounded retry closes the gap.
+
+    Any other GiteaError propagates immediately so the §13.3
+    orchestrator can fail the step and run rollback.
+    """
+    last_error: GiteaError | None = None
+    for attempt in range(1, attempts + 1):
+        try:
+            await gitea.merge_pull(
+                org, meta_repo, pr_number,
+                merge_message_title=merge_message_title,
+                merge_message_body=merge_message_body,
+                style="merge",
+            )
+            return
+        except GiteaError as e:
+            detail = (e.detail or "").lower()
+            if not any(hint in detail for hint in _MERGE_TRANSIENT_HINTS):
+                raise
+            last_error = e
+            log.warning(
+                "merge_pull transient (attempt %d/%d) for %s/%s#%d: %s",
+                attempt, attempts, org, meta_repo, pr_number, e.detail,
+            )
+            if attempt < attempts:
+                await asyncio.sleep(delay_seconds)
+    assert last_error is not None
+    raise last_error
 
 
 @dataclass(frozen=True)
@@ -823,14 +879,29 @@ class Bot:
     ) -> None:
         """§13.3 step 4: auto-merge the graduation PR with the admin as
         merge actor. Distinct action_kind so the audit log carries the
-        graduation as a linkable sequence per §13.3's transactional shape."""
+        graduation as a linkable sequence per §13.3's transactional shape.
+
+        Gitea computes a PR's mergeability asynchronously in a background
+        job. Step 3 (`open_graduation_pr`) returns the moment the PR is
+        created, which is typically before that job has finished — calling
+        `merge_pull` immediately produces a `405 "Please try again later"`
+        and the §13.3 orchestrator interprets it as a terminal failure.
+        We wait for the mergeability computation to settle before the
+        merge call, then retry the merge a couple of times if Gitea still
+        reports the transient state (belt-and-suspenders against the same
+        race appearing in a different shape).
+        """
         subject = f"Graduate {slug} → {rfc_id}"
         body = _trailer(actor)
-        await self._gitea.merge_pull(
-            org, meta_repo, pr_number,
-            merge_message_title=subject,
-            merge_message_body=body,
-            style="merge",
+
+        try:
+            await self._gitea.wait_for_mergeable(org, meta_repo, pr_number)
+        except TimeoutError as e:
+            raise GiteaError(409, str(e)) from e
+
+        await _merge_with_retry(
+            self._gitea, org, meta_repo, pr_number,
+            merge_message_title=subject, merge_message_body=body,
         )
         _log(
             actor,