docs(code-runtime-python): correct the claims the new backend invalidated

Adding a published Python backend and reordering `flush_line` left several
owning documents stating things that are no longer true.

`src/invariant.ts` justified its empty installer with "ships only the fd-3
wire-protocol codec", which the subprocess execution path contradicts. The
reason now states the actual one: every relation this backend maintains lives
in the CPython child or on the fd-3 wire, so no same-process event sequence is
observable from a listener -- the same shape the sibling worker-thread backend
uses.

The seam's `PORTABLE_RESERVED_WORDS` and `language` JSDoc, the code-runtime
README pair, and docs/subsystems/code-runtime both said only TypeScript has a
published backend. Corrected in all four, with the generated cordis catalog
regenerated for the `language` change.

The note attributed the 12x multiple to the settlement flush holding three
copies. That stopped being true when `flush_line` was reordered to drop the
pending chunks before its push: the binding worst case is the newline path's
single near-budget write. Corrected in the note (both sides) and in the test
comment that repeated it.

The note's Testing section now registers the cases this stack added, and the
Chinese side receives the O(depth) entry it never got plus the new ones -- it
had drifted from the English.

`INTERPRETER_BASELINE_BYTES` argued 64 MiB from a RESIDENT set while RLIMIT_AS
bounds address space. It now cites the bootstrap's own measurement (30.23 MiB
of mappings for `python3 -I`), making 64 MiB roughly twice the measured
baseline.

Also: a hardcoded `(:232-235)` comment reference becomes a reference by name,
a "which now walks in O(depth) too" change narrative becomes a current-state
statement, and a stray double blank line is removed.

packages/code-runtime/code-runtime/README.md

@@ -41,7 +41,7 @@ const result = await ctx.codeRuntime.run({
 
 ### Choose a backend
 
-Backends declare two descriptors you can rely on: `language` — what the program must be written in, with `'typescript'` and `'python'` as the well-known values and only TypeScript shipped — and `isolation` — the execution substrate (`'worker-thread'`, `'process'`, `'container'`), a label for deployments and diagnostics, not a security claim. The shipped backend is [`dsh-code-runtime-worker-thread`](../code-runtime-worker-thread/README.md), which executes TypeScript in a fresh Node worker thread; [`dsh-code-runtime-python`](../code-runtime-python/README.md) owns the wire protocol for the CPython backend.
+Backends declare two descriptors you can rely on: `language` — what the program must be written in, with `'typescript'` and `'python'` as the well-known values and both backed by published providers — and `isolation` — the execution substrate (`'worker-thread'`, `'process'`, `'container'`), a label for deployments and diagnostics, not a security claim. [`dsh-code-runtime-worker-thread`](../code-runtime-worker-thread/README.md) executes TypeScript in a fresh Node worker thread; [`dsh-code-runtime-python`](../code-runtime-python/README.md) executes Python in a fresh CPython subprocess.
 
 ### Name your bindings portably
 
@@ -98,7 +98,7 @@ Read these when the package-level contract is not enough. They move from the PTC
 
 - [PTC mode Agent Note](../../../.agents/notes/implemented/feature/2026-06-15-ptc.md) — how the tool registry consumes `ctx.codeRuntime` and presents `run_code` to the model.
 - [Worker-thread backend](../code-runtime-worker-thread/README.md) — the shipped TypeScript execution backend.
-- [Python protocol package](../code-runtime-python/README.md) — the wire protocol for the CPython backend.
+- [Python backend](../code-runtime-python/README.md) — the CPython subprocess execution provider and its fd-3 protocol.
 - [Code runtime subsystem reference](../../../docs/subsystems/code-runtime.md) — request/result vocabulary, bindings, and the `ctx.codeRuntime` cordis surface.
 - [Capability seams](../../../.agents/notes/implemented/architecture/2026-06-13-capability-seams.md) — the Service Definition / Service Provider / Consumer split.