docs: runtime migration, mark PR 02c as merged

The README asks whoever merges a plan's PR to move its row in "The
sequence" from `planned` to `merged`. PR 02c landed in #15153, so the
row now says so.

This matters beyond bookkeeping: Phase 0 states that every PR that
changes a Deno or std count lands after 02c, and the next plans
(00a onwards) check their dependencies against this table at step 0.

Author: cderv

dev-docs/runtime-migration/README.md

@@ -194,7 +194,7 @@ Every PR that changes a count lands after 02c; preparing it earlier is fine.
 | PR | Plan | What | Depends on | Executor | Size | Status |
 |---|---|---|---|---|---|---|
 | 02 | [02-runtime-boundary-check.md](02-runtime-boundary-check.md) | CI ratchet counting `Deno.*` and direct std imports in five scopes (`src`, `src-js`, `resources`, `package/src`, `tests`); `tests/asserts.ts`; lands first | none | Sonnet | S | in progress |
-| 02c | [02c-ratchet-pr-delta-and-guidance.md](02c-ratchet-pr-delta-and-guidance.md) | PR runs compare with the base branch; findings name a working replacement or ask the maintainer to accept; `--accept-increase` | 02 | Sonnet | S | planned |
+| 02c | [02c-ratchet-pr-delta-and-guidance.md](02c-ratchet-pr-delta-and-guidance.md) | PR runs compare with the base branch; findings name a working replacement or ask the maintainer to accept; `--accept-increase` | 02 | Sonnet | S | merged |
 | 00a | [00a-deno-bump.md](00a-deno-bump.md) | Deno 2.7.14 → newest 2.9.x everywhere the version appears | 02 | Sonnet | S | planned |
 | 00b | [00b-lockfile-and-bundle-gate.md](00b-lockfile-and-bundle-gate.md) | Committed `deno.lock` with `--frozen` (six entrypoints); `tools/check-test-imports.ts` keeps the unlocked tests inside that graph; three-OS bundle gate (cold cache, external-specifier grep, five renders) | 02, 00a | Opus | M | planned |
 | 00c | [00c-quarto-run-deprecation-notice.md](00c-quarto-run-deprecation-notice.md) | One-time notice when `quarto run` or a pre/post-render `.ts` script runs on Deno; `QUARTO_RUN_DENO_NOTICE=0` | 02 | Sonnet | S | planned |