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

README.md

@@ -548,6 +548,7 @@ You're never locked in. The system adapts.
 | `/gsd:quick [--full] [--discuss] [--research]` | Execute ad-hoc task with GSD guarantees (`--full` adds plan-checking and verification, `--discuss` gathers context first, `--research` investigates approaches before planning) |
 | `/gsd:health [--repair]` | Validate `.planning/` directory integrity, auto-repair with `--repair` |
 | `/gsd:stats` | Display project statistics — phases, plans, requirements, git metrics |
+| `/gsd:profile-user [--questionnaire] [--refresh]` | Generate developer behavioral profile from session analysis for personalized responses |
 
 <sup>¹ Contributed by reddit user OracleGreyBeard</sup>