fix: add some abstraction in place

[Anmol1696]

No description provided.

[Copilot]

Pull request overview

This PR adds code abstraction and improves localhost development support. The main goal is to reduce code duplication by extracting repeated header extraction logic and to enhance the local development experience by properly generating localhost URLs with configurable ports.

• Extracted header extraction logic into a reusable getHeaders function to eliminate duplication
• Added localhost detection and protocol/port handling for local development URLs
• Updated documentation and configuration to support the new LOCAL_APP_PORT environment variable

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
jobs/knative-job-fn/src/index.ts	Refactored duplicate header extraction code into a new getHeaders function used in middleware and error handling
functions/send-email-link/src/index.ts	Added localhost detection logic and support for configurable local development ports with http protocol for dry-run mode
jobs/DEVELOPMENT_JOBS.md	Added documentation explaining localhost resolution and LOCAL_APP_PORT behavior
functions/send-email-link/README.md	Documented the new LOCAL_APP_PORT environment variable
docker-compose.jobs.yml	Added LOCAL_APP_PORT environment variable configuration with default value of 3000

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