Update manual Firestore database setup

[qayshp]

Summary

• update the manual setup guide for Google's current Databases & Storage > Firestore navigation
• retain the alternate Build > Firestore Database path for users who still see the Firebase layout
• document the required database ID, edition, mode, initial rules selection, and permanent location choice
• preserve the existing Rules step so the separate security-rules PR can merge independently

Why

Google's current console no longer consistently matches the existing two-step Create database > Next > Enable instructions. The expanded flow prevents users from guessing which database edition and compatibility mode BlueBubbles expects.

Fixes BlueBubblesApp/bluebubbles-server#823.

Scope

This PR updates the database-creation flow only. It does not change the later Firestore security-rule recommendation, which is addressed separately in BlueBubblesApp/bluebubbles-server#783 and docs PR #34.

Validation

• walked through the current Firebase console flow read-only on July 23, 2026
• confirmed the current navigation, action labels, edition, database ID, mode, rules preset, and location wording
• ran git diff --check origin/master...HEAD
• simulated merging docs PRs Update manual Firestore database setup #31 and Secure manual Firestore setup rules #34 in both orders; both sequences merge without a conflict and pass git diff --check

No Firebase database was created and no account state changed. A screenshot is intentionally omitted because the vendor UI can drift; the text covers both observed navigation variants.

[qayshp]

Self-review completed. I found one documentation detail to tighten before this draft is ready.

[qayshp]

Validation update

• Walked through the current Firebase console flow read-only on this SIP-enabled Mac.
• Confirmed the current navigation, action labels, edition, database ID, mode, rules preset, and location wording.
• Updated the guide to match that live flow in commit 513f150.
• Stopped before creating a database, so no Firebase project or account state changed.
• git diff --check origin/master...HEAD passes.

No production screenshot asset is recommended for this change: the vendor UI is prone to drift, while the corrected text now covers both observed navigation variants.

This page also overlaps PR #34. When either branch is rebased, the final version must preserve both this corrected creation flow and #34's scoped security rules.

[qayshp]

Merge-readiness update: commit e8a1a79 keeps the expanded database-creation guidance inside the original step structure, leaving the Rules step unchanged for PR #34. git diff --check and the Markdown structure/link checks pass. Simulated merges of #31 and #34 pass in both orders with the combined content intact.