docs(quickstart): declare the compile timing as machine-variable (#260)

`content/docs/quickstart.mdx`'s Path B block publishes `✓ Build complete
(72ms)`. Every other visible byte in both blocks is deterministic; that
number is whatever the transcribing machine measured — `117ms` at CLI
17.1.0, `72ms` at 17.2.0, with no behavioural change behind the difference.

The block is a faithful transcript, so the number stays exactly as captured.
What changes is the declaration sentence that already tells the reader which
parts of their own output will differ: it named the expanded project paths
but not the timing, so a reader whose scaffold compiles in 300ms had no way
to know that is expected rather than a symptom. The timing now sits in that
same list.

Second effect: the recurring re-transcription of these blocks at each CLI
publish no longer has to justify a one-line timing change as drift, because
the value is declared rather than asserted.

Path A checked for the same shape and needs nothing: its published lines
carry no measured value. Verified against `@objectstack/cli` 17.2.0 source
rather than by re-booting — `printServerReady` (the banner both paths share)
interpolates no duration, `start.ts` prints no timer at all, and the only
`Build complete` timer in the CLI is on the compile path Path B exercises.


Claude-Session: https://claude.ai/code/session_01ChPQM8jamxLUfUAxwFpJ8S

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-bill

content/docs/quickstart.mdx

@@ -197,10 +197,11 @@ You'll see:
 
 That block is transcribed from `pnpm dev` on a scaffold created by
 `@objectstack/cli` 17.2.0. Project paths show as `my-app/…` — the CLI prints
-yours expanded. Your own run also prints pnpm's script header above the block,
-per-step compile progress, startup advisories (configuration load, dev
-secret-field crypto), the full list of loaded plugin names, boot diagnostics,
-and an MCP connection trailer below the banner.
+yours expanded, and the `Build complete` timing is whatever the transcribing
+machine measured, so yours will differ. Your own run also prints pnpm's script
+header above the block, per-step compile progress, startup advisories
+(configuration load, dev secret-field crypto), the full list of loaded plugin
+names, boot diagnostics, and an MCP connection trailer below the banner.
 
 Note the dev server asks for port **3000**, the same port `os start` uses. If
 that port is taken it binds the next free one and says so: