chore: planning gate — milestones, issues, and task breakdown

Break PRD into 8 milestones (Phase 0–7) with 59 issues on Gitea.
Populate TASKS.md, update mission manifest, initialize scratchpad.
Repo created at git.mosaicstack.dev/mosaic/mosaic-stack.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -0,0 +1,30 @@
+# Agent Guidelines
+
+## Required Load Order
+
+1. `~/.config/mosaic/SOUL.md`
+2. `~/.config/mosaic/STANDARDS.md`
+3. `~/.config/mosaic/AGENTS.md`
+4. `~/.config/mosaic/guides/E2E-DELIVERY.md`
+5. `AGENTS.md` (this file)
+6. Runtime-specific guide: `~/.config/mosaic/runtime/<runtime>/RUNTIME.md`
+7. `.mosaic/repo-hooks.sh`
+
+## Session Lifecycle
+
+```bash
+bash scripts/agent/session-start.sh
+bash scripts/agent/critical.sh
+bash scripts/agent/session-end.sh
+```
+
+## Shared Tools
+
+- Quality and orchestration guides: `~/.config/mosaic/guides/`
+- Shared automation tools: `~/.config/mosaic/tools/`
+
+## Repo-Specific Notes
+
+- Add project constraints and workflows here.
+- Implement hook functions in `.mosaic/repo-hooks.sh`.
+- Scratchpads are mandatory for non-trivial tasks.