feat(skills): restore 60 bundled skills (#42)

* feat(skills): restore ansible skill * feat(skills): restore api-tester skill * feat(skills): restore aws skill * feat(skills): restore azure skill * feat(skills): restore ci-cd skill * feat(skills): restore code-reviewer skill * feat(skills): restore compliance skill * feat(skills): restore confluence skill * feat(skills): restore crypto-expert skill * feat(skills): restore css-expert skill * feat(skills): restore data-analyst skill * feat(skills): restore data-pipeline skill * feat(skills): restore docker skill * feat(skills): restore elasticsearch skill * feat(skills): restore email-writer skill * feat(skills): restore figma-expert skill * feat(skills): restore gcp skill * feat(skills): restore git-expert skill * feat(skills): restore github skill * feat(skills): restore golang-expert skill * feat(skills): restore graphql-expert skill * feat(skills): restore helm skill * feat(skills): restore interview-prep skill * feat(skills): restore jira skill * feat(skills): restore kubernetes skill * feat(skills): restore linear-tools skill * feat(skills): restore linux-networking skill * feat(skills): restore llm-finetuning skill * feat(skills): restore ml-engineer skill * feat(skills): restore mongodb skill * feat(skills): restore nextjs-expert skill * feat(skills): restore nginx skill * feat(skills): restore notion skill * feat(skills): restore oauth-expert skill * feat(skills): restore openapi-expert skill * feat(skills): restore pdf-reader skill * feat(skills): restore postgres-expert skill * feat(skills): restore presentation skill * feat(skills): restore project-manager skill * feat(skills): restore prometheus skill * feat(skills): restore prompt-engineer skill * feat(skills): restore python-expert skill * feat(skills): restore react-expert skill * feat(skills): restore redis-expert skill * feat(skills): restore regex-expert skill * feat(skills): restore rust-expert skill * feat(skills): restore security-audit skill * feat(skills): restore sentry skill * feat(skills): restore shell-scripting skill * feat(skills): restore slack-tools skill * feat(skills): restore sql-analyst skill * feat(skills): restore sqlite-expert skill * feat(skills): restore sysadmin skill * feat(skills): restore technical-writer skill * feat(skills): restore terraform skill * feat(skills): restore typescript-expert skill * feat(skills): restore vector-db skill * feat(skills): restore wasm-expert skill * feat(skills): restore web-search skill * feat(skills): restore writing-coach skill
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+---
+name: sqlite-expert
+description: "SQLite expert for WAL mode, query optimization, embedded patterns, and advanced features"
+---
+# SQLite Expert
+
+A database specialist with deep expertise in SQLite internals, performance tuning, and embedded database patterns. This skill provides guidance for using SQLite effectively in applications ranging from mobile apps and IoT devices to server-side caching layers and analytical workloads, leveraging its advanced features well beyond simple key-value storage.
+
+## Key Principles
+
+- Enable WAL mode (PRAGMA journal_mode=WAL) for concurrent read/write access; it allows readers to proceed without blocking writers and vice versa
+- Use PRAGMA busy_timeout to set a reasonable wait duration (e.g., 5000ms) instead of receiving SQLITE_BUSY errors immediately on contention
+- Design schemas with appropriate indexes from the start; SQLite's query planner relies heavily on index availability for efficient execution plans
+- Keep transactions short and explicit; wrap related writes in BEGIN/COMMIT to ensure atomicity and reduce fsync overhead
+- Understand that SQLite is serverless and single-file; its strength is simplicity and reliability, not high-concurrency multi-writer workloads
+
+## Techniques
+
+- Set performance PRAGMAs at connection open: journal_mode=WAL, synchronous=NORMAL, cache_size=-64000 (64MB), mmap_size=268435456, temp_store=MEMORY
+- Use FTS5 for full-text search: CREATE VIRTUAL TABLE docs USING fts5(title, body) with MATCH queries and bm25() ranking
+- Query JSON data with the JSON1 extension: json_extract(), json_each(), json_group_array() for document-style data stored in TEXT columns
+- Write recursive CTEs (WITH RECURSIVE) for tree traversal, graph walking, and generating series of values
+- Use window functions (ROW_NUMBER, LAG, LEAD, SUM OVER) for running totals, rankings, and time-series analysis without self-joins
+- Create covering indexes that include all columns needed by a query to enable index-only scans (verified with EXPLAIN QUERY PLAN showing COVERING INDEX)
+- Implement UPSERT with INSERT ... ON CONFLICT (column) DO UPDATE SET for atomic insert-or-update operations
+
+## Common Patterns
+
+- **Multi-database Access**: Use ATTACH DATABASE to query across multiple SQLite files in a single connection, joining tables from different databases
+- **Application-defined Functions**: Register custom scalar or aggregate functions in your host language for domain-specific computations inside SQL queries
+- **Incremental Vacuum**: Use PRAGMA auto_vacuum=INCREMENTAL with periodic PRAGMA incremental_vacuum to reclaim space without a full VACUUM lock
+- **Schema Migration**: Use PRAGMA user_version to track schema version and apply migration scripts sequentially on application startup
+
+## Pitfalls to Avoid
+
+- Do not open multiple connections with different PRAGMA settings; WAL mode and other PRAGMAs should be set consistently on every connection
+- Do not use SQLite for high-concurrency write workloads with dozens of simultaneous writers; consider PostgreSQL or another client-server database instead
+- Do not store large BLOBs (over 1MB) inline; SQLite performs better when large objects are stored as external files with paths referenced in the database
+- Do not skip EXPLAIN QUERY PLAN during development; without it, slow full-table scans go unnoticed until production load reveals them