test: retire relay, preload and shared cases that re-prove an owned contract (#24007)

Audit sweep over `src/relay`, `src/preload` and `src/shared` (1,087 test files
reviewed). 101 case declarations removed across 40 files, 6 test files deleted
outright, 1,143 lines gone. Executed-case count falls further, since several
removals were `it.each` tables.

Dominant patterns, by frequency:

- Self-comparisons that cannot fail: `expect(f(x)).toBe(f(x))`,
  `JSON.parse(JSON.stringify(literal))` deep-equalling the literal for a type
  with no codec, and `normalizeKeyToken(t) === normalizeKeyToken(t)` presented as
  proof of memoization.
- Object literals asserting their own fields back, where the guarantee comes from
  the type annotation and the runtime assertion cannot fail.
- Copied inventories: constants compared to their own initializers, and a
  function returning a copy of an exported constant checked against that
  constant's literal contents.
- Duplicate invocations of a contract owned at a stronger boundary, including
  provider-local replays of a shared helper.
- Table rows varying a field production never reads, so every row runs one path.
- Names promising more than the input exercises: a "Windows launch" case in a
  module with no platform input, and a case whose named branch is never entered.

Two production symbols go with them, each a test-only export whose sole caller
was a deleted case:

- `getGitHubProjectRefInputByteLength` — a one-line forward to
  `getClipboardTextByteLength`. The real bound
  (`GITHUB_PROJECT_REF_INPUT_MAX_BYTES`) and its guard stay.
- `GRAB_STYLE_PROPERTIES` — an intended shared source of truth that nothing ever
  consulted; the property set is hand-enumerated at three independent sites.

One case was deliberately restored and strengthened rather than dropped. The
relay integration suite is the only place the real `SshChannelMultiplexer` is
wired to `RelayDispatcher`, so it reaches transport behavior the handler suites
cannot (they use `createMockDispatcher`). Its `fs.writeFile` roundtrip is the one
case producing a void result, and `JSON.stringify` drops an absent `result`
member — a shape no other surviving case exercises. Restored with an assertion
pinning what the client actually observes: `null`, not `undefined`. That
assertion failed on first run, so the fact was previously unasserted anywhere.

One deletion was reverted mid-audit. A case asserting that optional fields stay
invisible to "old attach and ready decoders" builds those decoders from `z.object`
schemas declared in the test file, so it demonstrates zod's unknown-key stripping
rather than anything shipped. It is nonetheless the only forward-compatibility
coverage these envelopes have, and `reliability-gates.jsonc:6232` names it as
evidence verbatim, so it stays. Note that `check-reliability-gates.mjs` passed
both with and without it: the script resolves manifest paths and commands, and
does not check that a named assertion still corresponds to a live case.

Kept deliberately: everything a reliability gate cites as evidence; the three
`registers all expected handlers` RPC manifests (a dropped registration is a
silent wire break no type checker catches, and one carries the STA-4571
`pty.ackData` ratchet); the `child-process` direct-import ratchet; and
prototype-spy cases paired with a `.repeat(10_000)` input, which assert a real
memory bound rather than merely forbidding a technique.

Verified: `pnpm test src/shared src/relay src/preload` (1073 files, 11996
passed, 1 pre-existing `it.fails`, 131 skipped), `pnpm tc` after clearing
`.tsbuildinfo`, `check-reliability-gates.mjs` (140 gates),
`check:code-quality:changed` (0 new findings).

src/shared/github/project-ref-input.ts

@@ -1,12 +1,8 @@
-import { getClipboardTextByteLength, isClipboardTextByteLengthOverLimit } from '../clipboard-text'
+import { isClipboardTextByteLengthOverLimit } from '../clipboard-text'
 
 export const GITHUB_PROJECT_REF_INPUT_MAX_BYTES = 2 * 1024
 export const GITHUB_PROJECT_REF_INPUT_TOO_LARGE_ERROR = 'Project reference is too large to resolve.'
 
-export function getGitHubProjectRefInputByteLength(input: string): number {
-  return getClipboardTextByteLength(input)
-}
-
 export function isGitHubProjectRefInputTooLarge(
   input: string,
   maxBytes = GITHUB_PROJECT_REF_INPUT_MAX_BYTES