Add fuzzy scheduling support for weekly schedules

[Copilot]

Weekly schedules previously required explicit times (e.g., weekly on monday at 06:30), causing all workflows to run simultaneously and creating load spikes. This adds fuzzy scheduling for weekly patterns to distribute execution times.

Changes

New fuzzy schedule patterns:

• weekly - Scatters across any weekday and time (10,080 possible slots)
• weekly on <day> - Scatters time on specific weekday (1,440 slots)
• weekly on <day> around HH:MM - Scatters within ±1 hour of target time (120 slots)

Implementation:

• Added FUZZY:WEEKLY, FUZZY:WEEKLY:<day>, and FUZZY:WEEKLY_AROUND:<day>:HH:MM patterns
• Deterministic scattering using workflow identifier as seed (consistent across recompilations)
• IsWeeklyCron() helper to detect fixed weekly patterns
• Compiler warnings for fixed weekly schedules

Example:

# Old (fixed time, load spikes)
schedule: weekly on monday at 06:30

# New (fuzzy, distributed)  
schedule: weekly on monday          # Scattered time on Mondays
schedule: weekly on friday around 5pm  # 4-6 PM window on Fridays
schedule: weekly                    # Any weekday, any time

Fixed weekly schedules still work but emit warnings recommending fuzzy alternatives.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/user
  • Triggering command: /usr/bin/gh gh api user --jq .login -json GO111MODULE ache/go/1.25.0/x64/pkg/tool/linux_amd64/link GOINSECURE GOMOD GOMODCACHE ache/go/1.25.0/xTest User env 2593034/b370/console.test GO111MODULE 2593034/b370/importcfg.link GOINSECURE GOMOD GOMODCACHE SKxUVknvXufI3/2ZUc9vejZHNutLcI0T/var/run/docker/runtime-runc/moby (http block)
  • Triggering command: /usr/bin/gh gh api user --jq .login (http block)
  • Triggering command: /usr/bin/gh gh api user --jq .login -json GO111MODULE 1/x64/bin/node 44d029610ffef2175685fe8cbf023ab79e6/log.json GOMOD GOMODCACHE go env 59/create_discussion.js GO111MODULE /opt/hostedtoolcache/go/1.25.0/x64/bin/go GOINSECURE GOMOD GOMODCACHE 08d1e7cc9018fe0e--bundle (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Add weekly support fo fuzz scheduling

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