docs(rfc): define and enforce a uniform RFC format; adopt it across the corpus

Define the in-file RFC contract in docs/rfc/README.md § The file format:
the header block (`# RFC: <title>` plus a dateless Status enum
cross-checked against the lifecycle folder), the per-lifecycle body
skeleton (a Problem opener everywhere; Proposal/Alternatives considered/
Acceptance criteria/Risks in proposed/; present-tense Decision/
Consequences with proposal-era headings banned in implemented/; the
frozen proposal shape in rejected/), and a mandatory Alternatives
considered section with a date-fenced grandfather comment for pre-format
RFCs whose alternatives are not reconstructible from the record.

Enforce it with a new doc-sync gate, scripts/verify-rfc-format.ts, and
normalize all 112 RFCs to it: ~15 Status-line spellings collapse to the
enum, 29 Context openers become Problem, the 39 legacy-format XXX debt
markers are resolved and banned from reappearing, proposal-era sections
in implemented RFCs are rewritten to shipped reality (including the
web/fs/subagent seam RFCs' migration plans and test checklists, closing
the doc-tiers deferred-work item on the web seam), every RFC gains an
Alternatives considered section or the grandfather comment, and the
bilingual pair is re-mirrored and re-recorded.

Move the generated index tables out of README.md into a fully generated
docs/rfc/INDEX.md — gen-rfc-index now writes the whole file, and
verify-rfc-classification checks its freshness and rejects index-shaped
rows in the curated README — which makes room for the format contract to
live in the README front door instead of a separate FORMAT.md.

The decision record, and the first RFC written in the new format, is
docs/rfc/implemented/process/2026-07-05-uniform-rfc-format.md.

docs/rfc/implemented/process/2026-06-11-vendor-cordis-as-source.md

@@ -1,10 +1,8 @@
 # RFC: Vendor Cordis as source, not npm dependencies
 
-Status: implemented (accepted 2026-06-11)
+Status: implemented
 
-<!-- XXX: legacy ADR/RFC body format, not yet normalized to a unified RFC template. -->
-
-## Context
+## Problem
 
 DeepSeek Harness SDK is built on the Cordis framework. Cordis core was at 4.0.0-rc.6 (a release candidate) when this repo started; the harness depends on framework internals (fiber lifecycle, effect disposal, waterfall dispatch) whose exact behavior matters to the agent loop's correctness guarantees.
 
@@ -14,6 +12,11 @@ Copy the needed Cordis packages (core, loader, include, group, timer, hmr, logge
 
 `vendor/README.md` is the manifest: upstream repo + commit SHA per package and an exhaustive local-modification log. A pre-commit guard (`scripts/check-vendor-manifest.sh`) rejects vendored-source changes that don't update the manifest in the same commit.
 
+## Alternatives considered
+
+- **Depend on the npm packages** — rejected: core was at a release candidate, and the harness leans on framework internals (fiber lifecycle, effect disposal, waterfall dispatch) whose exact behavior the agent loop's correctness guarantees depend on; an upstream RC bump could break them without a local fix path.
+- **Vendor everything transitively** — rejected: truly third-party dependencies (js-yaml, chokidar, @standard-schema/spec, …) stay on npm; only the framework layer whose internals matter is owned.
+
 ## Consequences
 
 - The harness fully owns its framework layer: auditable, patchable, pinned — an RC upstream can't break us, and we can fix framework bugs in-tree.