[armando-navarro]

Fixes #3834, #3683

This is the one docs PR for 22.0.0-rc.1. It stays a draft until the release.

Why one docs PR per release

• A docs change merged to main shows on GitHub as the current docs immediately, while the behavior it describes ships only in canaries until the next tagged release.
• Small docs PRs each cost a review and a branch, which slows things down.

How it works

• A code PR in 22.0.0-rc.1 that changes documented behavior does not carry the docs itself, and they get no PR of their own. They go here as one commit, added when the code PR is filed, and the code PR's description points here.
• This PR merges just before the 22.0.0-rc.1 tag, after the last code PR it describes, so the docs on main and the published package change together.
• A fix to docs for behavior that is already released normally goes in its own PR. While this PR is open it may ride here as its own commit instead, to save a review, and it is still cherry-picked to the 21 line on its own.
• Each commit message says which code PR it documents, so each commit can be reviewed on its own.

Commits so far

• docs: say which wrapped calls do not hold the app unstable, for fix: stop twelve wrapped calls from holding the app unstable #3827: lists in docs/zones.md the wrapped calls that do not hold the app unstable, and adds one sentence each under stateChanges, auditTrail and fromRef in docs/database.md.
• docs: describe firebase 13 support in the v22 upgrade guide, for feat: accept firebase 13 alongside firebase 12 #3831: states the supported range ^12.18.0 || ^13.0.0 and what ng update writes in docs/version-22-upgrade.md, updates the Yarn 1 and pnpm warning quotes, and adds a section on moving to firebase 13.
• docs: describe microtask delivery in the v22 upgrade guide, for feat(zones)!: deliver Observable read values as microtasks #3833: adds a section to docs/version-22-upgrade.md on Observable reads delivering at the next microtask checkpoint instead of after a timer, with the test-timing, setTimeout ordering and zoneless server render notes.
• docs: describe the callback pending-task change in the v22 upgrade guide, for feat(zones)!: remove callback pending tasks right after the callback #3837: adds a section to docs/version-22-upgrade.md on callback reads removing Angular's pending task right after the callback instead of one setTimeout(fn, 0) delay later: whenStable() and server rendering follow a callback read's first value one setTimeout(fn, 0) delay sooner, and a test that inspects pending tasks directly sees the task gone without a timer advance while a test awaiting whenStable() under fake timers still needs the advance.
• docs: say a handler passed as an observer object is wrapped too, for fix(core): wrap observer-object handlers like functions, and let a wrapped promise settle after teardown #3829: one sentence in docs/zones.md saying AngularFire re-enters the environment injector inside a handler passed as an observer object, such as { next, error }, the same as one passed as a function.
• docs(compat): add a setup section in NgModule and standalone form, for Docs: the compat setup (AngularFireModule.initializeApp) has had no page since the modular rewrite, and no standalone example #3683 (a docs fix for already-released behavior, riding here): a Setup section on docs/compat.md with the standalone and NgModule forms and the compat module of each product, and a pointer to it from the twelve compat pages that had an NgModule-only snippet or no setup at all.
• docs: say which package managers refuse an incompatible firebase, for build!: make firebase a peer dependency and add the v22 migration #3805 (a docs fix for already-released behavior, riding here): one sentence in docs/version-22-upgrade.md saying npm refuses an incompatible firebase that package.json requests, while Yarn and pnpm install it with a warning.
• docs: say which Firestore functions are not zone wrapped, for build(firestore): stop zone-wrapping functions that schedule no work #3842: a paragraph in docs/zones.md listing the Firestore functions re-exported without the zone wrapper, the switchMap example changed to a read, and the Verbose bullet limited to wrapped calls.
• docs(auth): build the server app with initializeBrowserOrServerApp, for feat(app): add initializeBrowserOrServerApp for browser & server apps #3844: step 4 of the server-side rendering section in docs/auth.md becomes the one call, the five details become three, a section relays the App Check token through the same cookie, server.ts sets Cache-Control: private, no-store, the manual callback stays in a "Building the app yourself" section that step 4 points at, the release modes say what a throwing ngOnDestroy does to a timed release, and docs/app-check.md and docs/version-22-upgrade.md point at the function.

Checklist

• Issue number for this PR: Document the 22.0.0-rc.1 changes #3834
• Docs included?: yes, this PR is docs only.
• Test units included?: no, docs only.
• Breaking change?: no
• In a clean directory, yarn install, yarn test run successfully?: not applicable, docs only.