Break up "Distributed Deployment" page into new "Scaling & Resilience" section (#2491)

* Add new Scaling landing page under Operations

Introduces a Scaling section with vertical vs. horizontal scaling
guidance and failover best practices, linking out to detail pages.

* Add new Vertical Scaling page

Dedicated how-to guidance for resizing existing nodes: when to scale
vertically, RAM sizing formulas, and Cloud/self-hosted resize steps.

* Add new Horizontal Scaling and Resilience page

Covers Raft consensus, the replication model, consistency guarantees,
Multi-AZ, and the resilience terminology used elsewhere in the docs.

* Move Distributed Deployment under Scaling and update all incoming links

Moves distributed_deployment.md into the new scaling/ section, trims
its Raft/Replication/Consistency intros into cross-links to the new
Horizontal Scaling and Resilience page, adds Multi-AZ and single-replica
cross-link callouts in the Cloud docs, rewrites all internal references
across ~30 files to the new canonical path instead of relying on
aliases, and applies Title Case to Distributed Deployment's headers.

* Split Resilience out of Horizontal Scaling and Resilience

Adds a dedicated Resilience page covering fault tolerance, Multi-AZ,
resilience terminology, and failover best practices (moved from the
Scaling landing page). Horizontal Scaling is retitled and scoped to
the underlying mechanics: Raft consensus, replication, and consistency.

* Reorganize Horizontal Scaling's structure

Moves "How Many Qdrant Nodes Should I Run?" from Distributed Deployment
into Horizontal Scaling, adds a conceptual Sharding section, and
reorders Sharding/Replication/Raft Consensus/Consistency. Moves the
remaining conceptual content out of Distributed Deployment: Temporary
Node Failure to Resilience, Error Handling folded into Replication,
sharding heuristics folded into Sharding, and the Consensus
Checkpointing explanation folded into Raft Consensus.

* Rename Scaling section to Scaling & Resilience

Renames the section and restructures the landing page: the vertical-
vs-horizontal decision is now purely about scaling, with a dedicated
Resilience section covering fault tolerance through sharding and
multi-node deployments.

* Polish Vertical Scaling and Resilience page content

Reframes Vertical Scaling's "What Not to Do" as positive "Best
Practices". Reworks Resilience's structure: moves the uptime/data-
integrity terminology into the intro as three distinct aspects of
resilience, and renames "How Resilience Works" to "Setting Up a
Resilient Qdrant Cluster".

* Add diagrams illustrating sharding and replication

Adds cluster diagrams to the Sharding and Replication sections on
Horizontal Scaling to make the shard/replica layout easier to follow.

* Add new Node Failure Recovery page

Extracts the node failure recovery scenarios out of Distributed
Deployment into their own page, with each bolded sub-header converted
to a proper heading, and links updated across Resilience and the
Scaling landing page.

* Add new Consistency Guarantees page

Extracts write consistency factor, read consistency, and write
ordering out of Distributed Deployment into their own page, positioned
after Distributed Deployment.

* Add new "Deploy Behind a Load Balancer" section

Explains why a load balancer is needed in front of a multi-node
Qdrant cluster: avoiding a single point of failure at the entry point
and making sure replicas on every node actually serve reads.

* Add new "Rebalancing" section

Documents how Qdrant Cloud automatically rebalances shards across
nodes, as its own subsection under Sharding.

* Rewrite Multi-AZ vs. Replication Factor as Multi-AZ Deployments

Defines an availability zone on first use, explains why multi-AZ
deployments guard against a zone going down, clarifies that Qdrant
Cloud is zone-aware once enabled, and that self-hosted deployments
need to place and move replicas across zones manually.

* Restructure node-count guidance into One/Two/Three-or-more Node subsections

Splits "How Many Qdrant Nodes Should I Run?" into three subsections
and drops the "balanced" framing for two nodes: it states plainly
that two nodes give more capacity without true high availability.

* Add new "Which Configuration Is Right for You?" section

Summarizes the one/two/three-or-more node tradeoffs in one place
right after the detailed breakdown.

* Add explicit _redirects entry for legacy distributed_deployment URL

Closes the redirect chain: the existing /guides/ and /operations/
legacy rules both terminate at /documentation/distributed_deployment/,
which previously had no explicit _redirects entry and only resolved
via the Hugo alias meta-refresh page.

* Fix all incoming links to Distributed Deployment and pages under Scaling

Repoints two same-page anchors in distributed_deployment.md that broke
when Write Ordering moved to Consistency Guarantees, and one link in
cloud/create-cluster.md that broke when a Resilience heading was
reworded.

* Update time-based sharding diagram and restructure section

* Fix a couple of broken links

* Move 'Consensus Checkpointing' to 'Node Failure Recovery' page

qdrant-landing/content/documentation/_index.md

@@ -112,7 +112,7 @@ Qdrant is an AI-native vector search engine for storing, indexing, and searching
 - [Managed Cloud](/documentation/cloud/index.md) — Qdrant as a managed service on AWS, GCP, or Azure with automatic scaling, backups, and zero-downtime upgrades.
 - [Hybrid Cloud](/documentation/hybrid-cloud/index.md) — Deploy into your own Kubernetes cluster while managing through Qdrant Cloud.
 - [Private Cloud](/documentation/private-cloud/index.md) — Fully air-gapped deployment in your own Kubernetes cluster with no Qdrant Cloud connectivity required.
-- [Distributed Deployment](/documentation/distributed_deployment/index.md) — Multi-node clusters with horizontal sharding and replication for scale and fault tolerance.
+- [Distributed Deployment](/documentation/scaling/distributed_deployment/index.md) — Multi-node clusters with horizontal sharding and replication for scale and fault tolerance.
 - [Security](/documentation/security/index.md) — API keys, JWT-based collection-scoped access control, TLS encryption, and network binding.
 - [Configuration](/documentation/ops-configuration/index.md) — Customize Qdrant via config files and environment variables; runtime administration tools; GPU-accelerated vector indexing.
 - [Monitoring & Telemetry](/documentation/ops-monitoring/index.md) — Monitor Qdrant with Prometheus and Grafana via built-in OpenMetrics endpoints.