Update create-package to handle all whitespace characters in sanitization

[Copilot]

The create-package tool's sanitization only handled spaces and underscores (tr ' _' '-'), but should convert any run of whitespace characters (spaces, tabs, etc.) into a single dash.

Changes

• Sanitization logic: Replace tr ' _' '-' with sed 's/[[:space:]]\+/-/g' to collapse any whitespace sequence into a single dash
• Documentation: Update README to reflect that whitespace runs (not just spaces/underscores) convert to single dashes
• Examples: Add test cases showing "my ^ repo2" → my-repo2 behavior

Example

# Before: "my  ^ repo2" → "my-repo2" (two spaces collapsed incorrectly)
# After: "my  ^ repo2" → "my-repo2" (any whitespace run correctly becomes single dash)

./create-package "my  ^ repo2"
# ✓ Created package 'my-repo2'
#   Script: my-repo2/my-repo2

# Also handles tabs and mixed whitespace
./create-package "test	with		tabs"
# ✓ Created package 'test-with-tabs'

Uses POSIX [[:space:]] class and \+ quantifier, compatible with standard sed on Debian/Ubuntu/Raspberry Pi.

Original prompt

Create a pull request in punppis/linux-utils to update the existing create-package tool sanitization and README documentation.

Context:

• There is an existing PR (Add create-package tool for scaffolding bash packages #1) on branch copilot/add-create-package-tool that adds create-package and README docs, but the sanitization currently uses tr ' _' '-'.

Required changes:

1. Update create-package sanitization to exactly match these rules:

• Lowercase everything.
• Convert any run of whitespace characters (spaces, tabs, etc.) into a single dash -.
• Remove all special characters.
• Allowed characters in final name: a-z, 0-9, and -.
• Collapse multiple dashes to a single dash and trim leading/trailing dashes.

Examples:

• "my repo" -> "my-repo"
• "my ^ repo2" -> "my-repo2"

2. Update README.md documentation to reflect the new whitespace rule (runs of whitespace -> single dash) and remove mention of underscores unless still supported explicitly.

Notes:

• Target environment: Debian/Ubuntu/Raspberry Pi; stick to standard tools available by default (bash, sed, tr).
• Ensure the tool still accepts package name from stdin or CLI args.

Acceptance criteria:

• ./create-package "my ^ repo2" creates directory my-repo2 and script my-repo2/my-repo2.
• Piped input works too.
• README matches the behavior.

This pull request was created from Copilot chat.

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