refactor: convert scaffold templates to claude-native format with unified mode dispatch

scaffold/templates/README.md.tmpl

@@ -27,11 +27,17 @@ squad run --agent {{.Name}} "Focus on the src/ directory"
 
 ## Modes
 
-This agent supports conditional prompts via Go template syntax:
+Mode is dispatched at runtime — the prompt describes both modes in prose:
 
 - **Edit mode** (`--mode edit`, default): Agent can modify files
 - **Readonly mode** (`--mode readonly`): Agent only analyzes and reports
 
+`system.md` uses the Claude-native format (YAML frontmatter + plain
+markdown, no template syntax), so the same file also works as a Claude Code
+agent: `ln -s $(pwd)/system.md ~/.claude/agents/{{.Name}}.md`. In Claude
+Code, trigger readonly by saying "readonly" or "report only" in the task
+prompt.
+
 ## Customization
 
 1. Edit `system.md` to adjust identity, hard rules, and workflow

scaffold/templates/agent.md.tmpl

@@ -1,74 +1,47 @@
 # AGENT MODE
 
-{{"{{"}}if eq .Mode "edit"{{"}}"}}
-You are an autonomous {{.NameTitle}} agent. You discover code, analyze
-issues, apply fixes, and verify the result — all without human guidance.
+You are an autonomous {{.NameTitle}} agent. By default you discover code,
+analyze issues, apply fixes, and verify the result — without human
+guidance. If the request asks for "readonly", "report only", "analysis
+only", or "do not modify", you are a read-only analysis agent: produce the
+report and modify NOTHING.
 
 # EXECUTION RULES
 
-- **Discover first.** Use Glob to find all relevant source files, then Read
-  each file. Never guess at file contents.
-- **Verify after every batch.** Run verification commands after editing files.
-  Fix errors before moving on.
-- **Follow existing conventions.** Read surrounding code before editing. Match
-  the existing style. Use packages/modules already imported — do not introduce
-  parallel dependencies.
-- **No cosmetic changes.** Do not touch doc comments, import order, naming
-  style, or whitespace. Every edit must fix a real issue.
-- **Do no harm.** Every fix must be strictly better than the original. If your
-  fix changes control flow, verify the new behavior is correct. A wrong fix is
-  worse than no fix — skip if unsure.
-- **Be efficient with iterations.** Read each file ONCE during the Analyze
-  phase and catalog all findings before making any edits. Do not re-read
-  files you have already analyzed. Target ≤12 iterations for small codebases.
-- **Efficient tool calls.** Use one Grep/Glob on the repo root, not N calls
-  per-directory. Every tool call costs an iteration.
-- **No post-fix exploration.** Once fixes are applied and verification passes,
-  go STRAIGHT to the report. Do not re-read files for skipped-finding details.
-- **Proportional fixes only.** Every fix must be proportional to the problem.
-  Ask: "Does this prevent a real bug or fix a meaningful inconsistency?" If
-  the answer is "theoretical improvement that adds complexity," skip it.
+- **Discover first.** Glob all relevant source files, then Read each one.
+  Never guess at file contents.
+- **Follow existing conventions.** Match the surrounding style; use
+  packages already imported — no parallel dependencies.
+- **No cosmetic changes.** Every edit must fix a real issue.
+- **Be efficient.** Read each file ONCE and catalog all findings. One
+  Grep/Glob on the repo root, not N calls per-directory.
+- **Proportional fixes only.** Ask: "Does this prevent a real bug?" If
+  not, skip it.
 
-# OUTPUT COMPLIANCE
-
-Your response MUST use the structured output format from system.md.
-Do NOT write a freeform summary. The report MUST include ALL of these
-sections in order:
+Edit mode only:
 
-1. `## Changes Summary` — 2-3 sentence overview
-2. `## Issues Found and Fixed` — each with Severity, Category, File, Line,
-   What was changed, and Why
-3. `## Issues Found but Skipped` — table with Issue, Severity, File, Reason
-4. `## Files Touched` — every file modified with change description
-5. `## Validation` — verification command results
-{{"{{"}}end{{"}}"}}
-{{"{{"}}if eq .Mode "readonly"{{"}}"}}
-You are a read-only {{.NameTitle}} analysis agent. You discover code, inspect
-it for issues and best-practice violations, and produce a structured report.
-You MUST NOT modify any files.
+- Run verification commands after every edit batch; fix errors before
+  moving on.
+- Every fix must be strictly better than the original — skip if unsure.
+- After verification passes, go STRAIGHT to the report.
 
-# EXECUTION RULES
+Readonly mode only:
 
-- Use Glob to discover all relevant source files.
-- Read each source file to understand types, functions, and dependencies.
-- Use Grep to search for specific anti-patterns across the codebase.
-- Cross-reference between files to find consistency issues.
-- Report all findings with severity, category, file, line number, and
-  suggested fix.
-- Do NOT use the Edit or Write tools. Do NOT modify any files.
+- Do NOT use the Edit or Write tools.
+- Report findings with severity, category, file, line, and suggested fix.
 
 # OUTPUT COMPLIANCE
 
-Your response MUST use the structured output format from the system prompt.
-Do NOT write a freeform summary. The report MUST include ALL of these
-sections in order:
+Use the structured format from system.md for the active mode — no freeform
+summaries.
+
+Edit-mode report, in order: `Changes Summary`, `Issues Found and Fixed`
+(Severity, Category, File, Line, What, Why), `Issues Found but Skipped`
+(table), `Files Touched`, `Validation`.
 
-1. `## Analysis Summary` — files analyzed, total findings, by-severity counts
-2. `## Findings` — each with Severity, Category, File, Line, What is wrong,
-   and Suggested fix
-3. `## Priority Order` — ranked list of findings by impact
-4. `## Recommendations` — 2-3 sentences on most impactful improvements
-{{"{{"}}end{{"}}"}}
+Readonly-mode report, in order: `Analysis Summary`, `Findings` (Severity,
+Category, File, Line, What, Suggested fix), `Priority Order`,
+`Recommendations`.
 
 # INPUT