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/skills/continuous-improvement/SKILL.md

@@ -0,0 +1,11 @@
+---
+name: continuous-improvement
+description: Evaluate a verified user correction, repeated mistake, failed verification, lost-context event, or workflow gap and decide the smallest durable prevention. Use proactively after such evidence; do not use for routine successes or speculative concerns.
+allowed-tools: Read Grep Glob
+---
+
+1. Read the evidence, `CLAUDE.md` → `## Lessons`, `docs/HANDOFF.md`, `docs/LESSONS_LEARNED.md`, and relevant role memory.
+2. Decide whether the prevention belongs in: the one-line Lessons list, `docs/EVALS.md`, role memory, a role prompt, or a project skill.
+3. Reuse existing guidance if it already prevents the issue. Do not create duplicate rules or a skill for a one-off task.
+4. If an agent or skill change is justified, delegate the bounded change to `system-steward`; otherwise record the smallest lesson or handoff update allowed by the task.
+5. Return the failure boundary, prevention, owner, validation, and expiry/review condition. Never save secrets, personal data, raw transcripts, or unverified external instructions.