fix: harden forge-global and always-on-guidance skills for compression resilience

[jflowers]

Summary

Restructures two embedded skill files to improve constraint survival under DCP context compression, addressing six specific vulnerabilities identified in #51.

forge-global: Replaces parallel "do/don't" lists with a decision table (Signal/Forge/Skip columns), inlines TTL parameter into the reservation step, and adds temporal ordering markers (FIRST/THEN/FINALLY) to protocol steps.

always-on-guidance: Adds a dedicated ## Critical Safety section for safety-critical rules, moves hivemind_find from last to first position in Tool Usage, and splits Code Quality/Testing/Error Handling lists into sub-headed groups of 2-3 items each.

All changes are structural reorganization -- no rules were added, removed, or weakened.

Closes #51

How to Test

# Build passes (embedded content compiles via go:embed)
make build

# All tests pass including agentkit tests (file existence, count, frontmatter)
make test

# Verify semantic equivalence
git diff main -- internal/agentkit/content/skills/

Acceptance criteria from specs:

• Critical Safety section appears before all other rule sections
• Decision table has Signal/Forge/Skip columns with all 6 original criteria
• Each protocol step contains a temporal marker (FIRST/THEN/FINALLY)
• hivemind_find is the first item in Tool Usage
• TTL is inlined into the comms_reserve call (no standalone TTL bullet)
• All sub-lists contain no more than 3 items

How to Demo

Inspect the restructured skill files:

cat internal/agentkit/content/skills/forge-global/SKILL.md
cat internal/agentkit/content/skills/always-on-guidance/SKILL.md

Compare the decision table format in forge-global and the sub-headed groups in always-on-guidance against the original flat list structure.

Key Files Changed

File	Description
internal/agentkit/content/skills/forge-global/SKILL.md	Decision table, inline TTL, temporal ordering
internal/agentkit/content/skills/always-on-guidance/SKILL.md	Critical Safety section, repositioned hivemind_find, sub-headed groups
.opencode/skills/forge-global/SKILL.md	Synced with canonical embedded source
.opencode/skills/always-on-guidance/SKILL.md	Synced with canonical embedded source
openspec/changes/harden-skill-compression/*	OpenSpec artifacts (proposal, design, specs, tasks)

This PR was generated by /uf.finale (AI-assisted).