[satya-sudo]

Description

Fixes #1847
Preserve dotenv declaration order when loading global and task-level environment
files. MIT liscense is added , The existing loaders copy godotenv's plain Go map into Task's ordered
variable store, losing declaration order. This makes nested global dotenv
{{.VAR}} references resolve inconsistently between runs.

Adapt the godotenv v1.5.1 parser into an internal package backed by the existing
ordered-map dependency, Both loaders use
this reader. Dollar expansion, quotes, parse errors, optional missing files and
first-file-wins precedence remain unchanged. No new dependency is added and no
public API is introduced.

Validation:

• go test ./...
• golangci-lint run using the pinned v2.14.0
• go build -o bin/task ./cmd/task and run the nested-path fixture
• The regression test fails against the original loaders with truncated paths.
• Regression coverage repeats the nested path and declaration-order checks
  50 times; parser tests cover syntax, quoting, multiline values, CRLF,
  duplicate keys, dollar expansion and error compatibility.

AI assistance was used to prepare tests and validation.

Checklist

• I have read and followed the Contribution Guide.
• I have disclosed the use of any AI-generated content in this pull request per the AI Usage Policy.
• I fully understand the changes and have hand-written the description (No AI) of this pull request.