feat: wire after_specify and after_plan hook events into command templates

[davidniu-0914]

Description

This PR aligns the extension hooks documentation and command templates for the specify and plan commands, resolving Issue #1788. It ensures that all core command templates (specify.md, plan.md, tasks.md,
implement.md) contain consistent CRITICAL execution instructions for mandatory hooks, preventing AI agents from proceeding before hook execution. Additionally, it synchronizes the project version to 0.2.1 across
pyproject.toml and all extension guides to match the upstream repository.

Testing

• Verified markdown template rendering and hook logic consistency across all modified command files.
• Confirmed version consistency in pyproject.toml and documentation.
• Tested locally with uv run specify --help
• Ran existing tests with uv sync && uv run pytest

AI Disclosure

• I did not use AI assistance for this contribution
• I did use AI assistance (describe below)

This PR was prepared with the assistance of Gemini CLI to synchronize version numbers across multiple files, standardize hook instructions in markdown templates for behavioral consistency, and ensure
documentation accuracy relative to the implemented features.

[Copilot]

Pull request overview

This PR updates the Spec Kit command templates and extension documentation so that the lifecycle hook events for before_specify/after_specify and before_plan/after_plan are represented consistently alongside existing hook points, and bumps the project/docs version to 0.2.1.

Changes:

• Add pre- and post- hook instructions for specify and plan command templates (before_* and after_* events).
• Strengthen “mandatory hook” execution instructions across core templates (add explicit CRITICAL “execute immediately” language).
• Bump version to 0.2.1 and update extension guides + changelog accordingly.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
templates/commands/specify.md	Adds before_specify and after_specify hook instructions + CRITICAL execution requirements.
templates/commands/plan.md	Adds before_plan and after_plan hook instructions + CRITICAL execution requirements.
templates/commands/tasks.md	Adds CRITICAL execution requirement wording for mandatory hooks.
templates/commands/implement.md	Adds CRITICAL execution requirement wording for mandatory hooks.
src/specify_cli/extensions.py	Updates docstrings/examples for hook event names to include specify/plan events.
pyproject.toml	Bumps package version to 0.2.1.
extensions/EXTENSION-USER-GUIDE.md	Updates stated minimum/version references and last-updated metadata.
extensions/EXTENSION-DEVELOPMENT-GUIDE.md	Expands documented hook points to include specify/plan + before_implement, updates examples.
extensions/EXTENSION-API-REFERENCE.md	Documents additional standard hook events and adds CRITICAL mandatory-hook instruction.
CHANGELOG.md	Adds an Unreleased entry for the new hook wiring.

Comments suppressed due to low confidence (2)

templates/commands/plan.md:87

• The post-plan hook filtering here will drop hooks that omit enabled (which are enabled by default in HookExecutor) and will skip all hooks that set condition, even though the codebase supports condition evaluation. This makes conditional hooks impossible to trigger from the template-driven workflow.

   - Filter to only hooks where `enabled: true`
   - For each remaining hook, do **not** attempt to interpret or evaluate hook `condition` expressions:
     - If the hook has no `condition` field, or it is null/empty, treat the hook as executable
     - If the hook defines a non-empty `condition`, skip the hook and leave condition evaluation to the HookExecutor implementation
   - For each executable hook, output the following based on its `optional` flag:

templates/commands/specify.md:33

• Hook filtering in the template doesn’t match the actual hook config behavior in HookExecutor: hooks default to enabled when the enabled field is missing (h.get('enabled', True)), so instructing the agent to keep only enabled: true would incorrectly drop hooks without an explicit enabled key. Also, skipping hooks with a non-empty condition means conditional hooks will never run from the template flow even though the codebase supports condition evaluation; consider treating conditions as evaluatable (same rules as HookExecutor.should_execute_hook) or at least not skipping them outright.

- Filter to only hooks where `enabled: true`
- For each remaining hook, do **not** attempt to interpret or evaluate hook `condition` expressions:
  - If the hook has no `condition` field, or it is null/empty, treat the hook as executable
  - If the hook defines a non-empty `condition`, skip the hook and leave condition evaluation to the HookExecutor implementation

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