feat: Implement Prompt Builder functionality in Popup and Options

- Added a new "Prompt Builder" tab in the Popup for generating AI prompts with customizable parameters.
- Introduced new state variables for managing prompt styles, personas, formats, and models.
- Enhanced the Options page to fetch and display models based on the provided API key.
- Updated the actions and types to include the new 'prompt' action and its associated parameters.
- Implemented migration logic for legacy plaintext API keys to encrypted storage.
- Updated the getSystemPrompt function to incorporate prompt parameters for better instruction generation.
- Added tests for the new functionality, including context menu entries and prompt generation logic.

.claude/AGENTS.md

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+# Project subagents
+
+The project-level Claude Code subagents live in `./agents/`. They are intentionally few and have distinct ownership:
+
+| Agent | Purpose | Write access | Default model |
+| --- | --- | --- | --- |
+| `fable-orchestrator` | frames, routes, and accepts verified work | no | Fable |
+| `scout` | maps code and constraints | no | Haiku |
+| `planner` | produces a minimal testable plan | no | Opus |
+| `builder` | implements a named, scoped change | yes | Sonnet |
+| `lexai-extension-dev` | LexAI-specific implementation (entrypoints, LLM proxy, key handling, selection/replace, Gitea/CWS release) | yes | Sonnet |
+| `verifier` | independently checks acceptance tests | no direct file tools | Haiku |
+| `critic` | adversarial review for high-risk work | no direct file tools | Opus |
+| `security-auditor` | authn/authz, secrets, injection, deps, attack surface | `docs/attacksurface.md` only | Opus |
+| `learning-steward` | turns proven mistakes into guardrails/evals | only lesson and eval artifacts | Haiku |
+| `system-steward` | improves agents, skills, and role memory from evidence | operating artifacts only | Opus |
+| `integrator` | combines independent named changes | yes | Sonnet |
+
+## Use
+
+Run Fable as the main session when the work needs coordination:
+
+```powershell
+claude --agent fable-orchestrator
+```
+
+`fable`, `opus`, `sonnet`, and `haiku` are version-flexible Claude Code aliases. They resolve to the newest enabled version for the current provider and account; this avoids leaving the project pinned to an obsolete model ID.
+
+For a one-off specialist, invoke it in a normal Claude Code session, for example:
+
+```text
+@scout Map the code paths and tests relevant to [task]. Do not modify files.
+@builder Implement the approved task contract for [task] in [paths].
+@lexai-extension-dev Implement [task] in entrypoints/ respecting the message contract and key-handling rules.
+@verifier Verify [task] against these acceptance tests: [tests].
+@security-auditor Audit [change/component] for authz, injection, secrets, and attack-surface exposure.
+@learning-steward Review this verified failure and decide the smallest durable prevention.
+@system-steward Improve the relevant project agent or skill only from this evidence: [evidence].
+```
+
+For LexAI code (anything under `entrypoints/` or `src/`), prefer `lexai-extension-dev` over the generic `builder` — it knows the message contract, snapshot pattern, and key-handling rules. Use `builder` for repo-agnostic changes (config, tooling, docs). Use no more than one implementer on the same files. For low-risk, isolated work, use a normal Claude Code session instead of adding coordination overhead.
+
+## Memory and skills
+
+Fable, Planner, Builder, Verifier, Critic, Learning Steward, Integrator, and System Steward use project-scoped role memory. It is committed under `.claude/agent-memory/` when Claude Code creates it, so the team can review it. Fable also uses Claude Code Auto Memory for session continuity.
+
+- `/resume-project`