feat(infra): distribute terraform modules under infra/terraform

POC: lift the homelab-grown nextcloud-mcp-server and
nextcloud-mcp-deployer-role Terraform modules into this repo so external
operators can consume them via a `git::` source.

Includes a top-level README documenting the two-phase deploy flow
(bootstrap deployer role with a copy-pasteable IAM policy, then assume the
role to deploy the MCP server) and supports both in-VPC Qdrant and
external/managed Qdrant modes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

infra/terraform/.gitignore

@@ -0,0 +1,12 @@
+.terraform/
+.terraform.lock.hcl
+*.tfstate
+*.tfstate.*
+*.tfvars
+*.tfvars.json
+crash.log
+crash.*.log
+override.tf
+override.tf.json
+*_override.tf
+*_override.tf.json