Fix pre-existing issues and update README for v2.0

- Fix _infer_state_from_artifacts: SPEC-only maps to research (was bug_find)
- Fix cmd_validate_folder: corrupted .state files now error instead of silent fallback
- Fix upgrade.sh: remove || true, add python3 check, use git rev-parse --git-dir
- Update README.md with --project flag, --can-edit modes, --upgrade, enforcement layers
- Add 6 new tests for inference and validation fixes
- Complete hook-install-process and readme-upgrade-docs tasks

tasks/readme-upgrade-docs/IMPLEMENTATION.md

@@ -0,0 +1,31 @@
+# Implementation: README and Upgrade Docs
+
+## Changes Made
+
+### 1. Quick Reference (README.md)
+- Added `--project /path/to/project` to every `status.py` command example
+- Added `--upgrade` and `--can-edit` commands with all 4 modes
+- Added note about `--project` being required with multiple projects
+
+### 2. Untracked Tasks Section
+- Documents that tasks without `.state` files are refused by all commands
+- Shows how to upgrade single tasks or all tasks at once
+
+### 3. Enforcement Section
+- Documents 3 enforcement layers: harness pre-edit hook, git pre-commit hook, prompt rules
+- References `contracts/harness-integration.md` for details
+
+### 4. Upgrading Section (rewritten)
+- "Updating the framework" (git pull) separated from "Upgrading to v2.0" (upgrade.sh)
+- Step-by-step upgrade.sh usage with what it does
+- Manual pre-commit hook installation
+- `--can-edit` verification step
+
+### 5. Project Setup Section
+- Option B (Manual Way) now includes pre-commit hook installation
+
+### 6. Key Components
+- Added `scripts/git-hooks/pre-commit`
+- Added `contracts/harness-integration.md`
+- Added `plugins/automaton-guard/`
+- Updated `scripts/status.py` description to mention `--can-edit`