docs: add developer profiling, execution hardening, and idempotent mark-complete to docs (#1108)

Update documentation for features added since v1.25.1:

- CHANGELOG.md: Add [Unreleased] entries for developer profiling pipeline,
  execution hardening (pre-wave check, cross-plan contracts, export
  spot-check), and idempotent requirements mark-complete

- README.md: Add /gsd:profile-user command to utilities table

- docs/COMMANDS.md: Add full /gsd:profile-user command documentation
  with flags, generated artifacts, and usage examples

- docs/FEATURES.md: Add Feature 33 (Developer Profiling) with 8
  behavioral dimensions, pipeline modules, and requirements; add
  Feature 34 (Execution Hardening) with 3 quality components

- docs/AGENTS.md: Add gsd-user-profiler agent documentation and
  tool permissions entry

docs/AGENTS.md

@@ -329,6 +329,29 @@ GSD uses a multi-agent architecture where thin orchestrators (workflow files) sp
 
 ---
 
+### gsd-user-profiler
+
+**Role:** Analyzes session messages across 8 behavioral dimensions to produce a scored developer profile.
+
+| Property | Value |
+|----------|-------|
+| **Spawned by** | `/gsd:profile-user` |
+| **Parallelism** | Single instance |
+| **Tools** | Read |
+| **Model (balanced)** | Sonnet |
+| **Color** | Magenta |
+| **Produces** | `USER-PROFILE.md`, `/gsd:dev-preferences`, `CLAUDE.md` profile section |
+
+**Behavioral Dimensions:**
+Communication style, decision patterns, debugging approach, UX preferences, vendor choices, frustration triggers, learning style, explanation depth.
+
+**Key behaviors:**
+- Read-only agent — analyzes extracted session data, does not modify files
+- Produces scored dimensions with confidence levels and evidence citations
+- Questionnaire fallback when session history is unavailable
+
+---
+
 ## Agent Tool Permissions Summary
 
 | Agent | Read | Write | Edit | Bash | Grep | Glob | WebSearch | WebFetch | MCP |
@@ -348,6 +371,7 @@ GSD uses a multi-agent architecture where thin orchestrators (workflow files) sp
 | ui-auditor | ✓ | ✓ | | ✓ | ✓ | ✓ | | | |
 | codebase-mapper | ✓ | ✓ | | ✓ | ✓ | ✓ | | | |
 | debugger | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | | |
+| user-profiler | ✓ | | | | | | | | |
 
 **Principle of Least Privilege:**
 - Checkers are read-only (no Write/Edit) — they evaluate, never modify