Add bi-weekly and tri-weekly schedule syntax with scattered execution times

[Copilot]

Adds bi-weekly and tri-weekly schedule syntax that distributes workflow execution times deterministically across 14-day and 21-day periods respectively.

Changes

Parser (pkg/parser/schedule_parser.go):

• Added bi-weekly and tri-weekly cases generating FUZZY:BI_WEEKLY and FUZZY:TRI_WEEKLY intermediate forms
• Implemented scattering across 20,160 minutes (14 days) for bi-weekly and 30,240 minutes (21 days) for tri-weekly
• Produces cron patterns with */14 and */21 day intervals respectively

Tests (pkg/parser/schedule_parser_test.go):

• Parse tests validating new keyword recognition
• Scatter tests verifying correct day intervals
• Deterministic tests ensuring consistent time assignment across recompilations

Documentation (docs/src/content/docs/reference/schedule-syntax.md):

• Added quick reference entries and dedicated sections for bi-weekly/tri-weekly
• Updated best practices section

Usage

on: bi-weekly    # Runs every 14 days at scattered time (e.g., "2 15 */14 * *")
on: tri-weekly   # Runs every 21 days at scattered time (e.g., "22 5 */21 * *")

Each workflow gets a deterministic execution time via FNV-1a hash of its path, preventing load spikes while ensuring consistency across compilations.

Original prompt

Add support for "bi-weekly" "tri-weekly" on short scheduling syntax. Scatter start day, hour and minute accross the week.

Custom agent used: agentic-workflows
GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing

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