Spec naming

[ulayera]

I'd like to have different options for spec name prefix, i personally prefer sequential numbers rather than the date (specially since i create most of the specs in a single day).

I changed it locally for me like this:

### Step 2: Initialize Spec Structure

Determine a kebab-case spec name from the user's description, then create the spec file:
```bash
# Determine kebab-case spec name from user's description
SPEC_NAME="[kebab-case-name]"

# Find the next sequential number by checking existing specs
SPECS_DIR="agent-os/specs"
mkdir -p "$SPECS_DIR"

# Get the highest existing spec number
LAST_NUM=$(ls "$SPECS_DIR"/spec-*.md 2>/dev/null | \
           sed 's/.*spec-\([0-9]*\)-.*/\1/' | \
           sort -n | \
           tail -1)

# If no specs exist, start at 1, otherwise increment
if [ -z "$LAST_NUM" ]; then
  NEXT_NUM=1
else
  NEXT_NUM=$((LAST_NUM + 1))
fi

# Format number with leading zeros (3 digits)
SPEC_NUM=$(printf "%03d" $NEXT_NUM)

# Create spec filename
SPEC_FILENAME="spec-${SPEC_NUM}-${SPEC_NAME}.md"
SPEC_PATH="$SPECS_DIR/$SPEC_FILENAME"

# Create the spec file
touch "$SPEC_PATH"

echo "Created spec file: $SPEC_PATH"
''' // bash block closing backticks replaced so github doesn't eat them

But it'd be great for the LLM or the installation script to ask:

Which format for specs:

• YYYY-DD-MM-spec-name.md
• spec-[seq-number]-spec name.md