Add local dev defaults and utility functions

[mspandey]

Description

Enhances the environment bootstrap workflow by automatically replacing empty or well-defined placeholder environment variable values (such as MONGO_URI, DATABASE_URL, and REDIS_URL) with sensible local development defaults when generating a .env file from .env.example.

This significantly reduces manual setup friction and improves the developer onboarding experience for first-time contributors.

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Changes Made

• **Added src/utils/envDefaults.ts**:

• Implemented LOCAL_DEV_DEFAULTS mappings for standard databases/services (MONGO_URI, DATABASE_URL, REDIS_URL).

• Added robust placeholder detection (isPlaceholderOrEmpty) to identify empty fields, bracketed tags (<your_database_url>), and keywords like YOUR_ or CHANGE_ME.

• Created applyLocalDevDefaults to parse .env lines, substitute matching keys safely, and preserve spacing, formatting, and comments.

• Integrated into Environment Bootstrap:

• Updated src/runners/EnvBootstrap.ts to process .env.example file contents through the defaults engine prior to writing out the generated .env.

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Testing Scenarios Verified

1. Empty Values:

• MONGO_URI= $\rightarrow$ MONGO_URI=mongodb://localhost:27017/<database-name>
• DATABASE_URL= $\rightarrow$ DATABASE_URL=postgresql://<username>:<password>@localhost:5432/<database-name>
• REDIS_URL= $\rightarrow$ REDIS_URL=redis://localhost:6379

2. Placeholder Values:

• MONGO_URI=YOUR_MONGODB_URI $\rightarrow$ Replaced with local dev default.
• DATABASE_URL=<your_database_url> $\rightarrow$ Replaced with local dev default.
• REDIS_URL=your_redis_url $\rightarrow$ Replaced with local dev default.

3. Preservation of Custom / Unrelated Values:

• Verified that user-provided valid connection strings (e.g., MONGO_URI=mongodb://localhost:27017/mydb) and unrelated environment variables (e.g., JWT_SECRET, API keys) remain completely unchanged.

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Benefits

• Smoother Onboarding: New contributors can spin up services locally right away without manually hunting down and configuring connection string syntaxes.
• Safety: Only targets specified service connection keys; leaves existing secrets and user configurations untouched.
  [Feature]: Generate Local Development Defaults for Placeholder Env Variables #32

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[ZarrarPeshimam]

@mspandey, why have u posted 2 PRs (#43 #44) for one issue?