feat(#769): adopt context:fork + effort on heavy workflow skills (#820)

* feat(#769): emit context:fork + effort: frontmatter on heavy workflow skills

Add `context: fork` and `effort: xhigh` to the three heaviest workflow
commands (plan-phase, execute-phase, autonomous) and `effort: low` to the
two quick-status commands (progress, stats).

On Claude Code, `context: fork` runs the skill in an isolated subagent
context window so the main session's context budget is protected.
`effort: xhigh` / `effort: low` signal the appropriate token-budget tier to
the runtime. Both fields are silently ignored by runtimes that do not
recognise them (Gemini, Codex, Cursor, etc.) — no behaviour change outside
Claude Code.

Update convertClaudeCommandToClaudeSkill in bin/install.js to preserve
`context:` and `effort:` when rewriting source command files to SKILL.md for
a Claude global install. Add install-suite tests to assert the fields are
present in both source commands and the installed SKILL.md output.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(#769): tighten regex assertions + add execute/plan-phase effort coverage

Fix low-severity adversarial finding: tighten test regex patterns from
`\s*` to `[ \t]*` so they cannot match across newlines (CRLF parity).
Add missing effort: xhigh assertions for gsd-execute-phase and gsd-plan-phase
SKILL.md install output to complete the black-box coverage gap.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

commands/gsd/autonomous.md

@@ -2,6 +2,8 @@
 name: gsd:autonomous
 description: Run all remaining phases autonomously — discuss→plan→execute per phase
 argument-hint: "[--from N] [--to N] [--only N] [--interactive]"
+context: fork
+effort: xhigh
 allowed-tools:
   - Read
   - Write

commands/gsd/execute-phase.md

@@ -2,6 +2,8 @@
 name: gsd:execute-phase
 description: Execute all plans in a phase with wave-based parallelization
 argument-hint: "<phase-number> [--wave N] [--gaps-only] [--interactive] [--tdd]"
+context: fork
+effort: xhigh
 allowed-tools:
   - Read
   - Write

commands/gsd/plan-phase.md

@@ -2,6 +2,8 @@
 name: gsd:plan-phase
 description: Create detailed phase plan (PLAN.md) with verification loop
 argument-hint: "[phase] [--auto] [--research] [--skip-research] [--research-phase <N>] [--view] [--gaps] [--skip-verify] [--prd <file>] [--ingest <path-or-glob>] [--ingest-format <auto|nygard|madr|narrative>] [--reviews] [--text] [--tdd] [--mvp]"
+context: fork
+effort: xhigh
 allowed-tools:
   - Read
   - Write

commands/gsd/progress.md

@@ -2,6 +2,7 @@
 name: gsd:progress
 description: Check progress, advance workflow, or dispatch freeform intent — the unified GSD situational command
 argument-hint: "[--forensic | --next | --do \"task description\"]"
+effort: low
 allowed-tools:
   - Read
   - Bash

commands/gsd/stats.md

@@ -1,6 +1,7 @@
 ---
 name: gsd:stats
 description: Display project statistics — phases, plans, requirements, git metrics, and timeline
+effort: low
 allowed-tools:
   - Read
   - Bash