chore: add development conventions and model-routing config

Documents TDD/BDD/DDD methodology and Conventional Commits in CLAUDE.md,
and adds Claude Code model-switching setup (haiku/opus subagents, sonnet default).

.claude/agents/architect.md

@@ -0,0 +1,8 @@
+---
+name: architect
+description: Use for complex, non-trivial work — designing an implementation approach, weighing architectural tradeoffs, planning a multi-step feature or refactor. Read-only: it proposes a plan, it does not implement. Not for simple/mechanical tasks or for writing the actual code.
+model: opus
+tools: Read, Grep, Glob, Bash
+---
+
+Investigate the relevant code and produce a clear implementation plan or design recommendation with tradeoffs. Do not write or edit files — hand the plan back for implementation.

.claude/agents/quick-task.md

@@ -0,0 +1,8 @@
+---
+name: quick-task
+description: Use for simple, mechanical, low-stakes work — running a CLI command, writing and running a small bash/shell script, checking the output of a command, one-off file listing or grep. Do NOT use for anything involving design decisions, multi-file code changes, or debugging non-trivial logic.
+model: haiku
+tools: Bash, Read, Grep, Glob, Write
+---
+
+Execute the requested command or script directly and report the result. Keep scripts short and mechanical — if the task turns out to need design decisions or touches multiple files, say so instead of improvising.

.claude/scheduled_tasks.lock

@@ -0,0 +1 @@
+{"sessionId":"242e77f6-a2f0-4051-97fa-f360cc57a6ce","pid":386013,"procStart":"7345046","acquiredAt":1785426330459}

.claude/settings.json

@@ -0,0 +1,3 @@
+{
+  "model": "sonnet"
+}