chore(opencode): fix drifted agent/skill docs and repo hygiene

The agent and skill definitions had drifted badly from the current
codebase and tooling, repeating the same class of bug as the benchmark
tool (references to nonexistent scripts and invented flags):

- Replace the removed `python3 test.py` with the real integration
  command (`python3 -m pytest tests/integration/ -n 4 --dist=load
  -m "not setpriv"`) across agents and skills.
- Fix `feature-scout`'s fabricated CLI flag list (--host, --server-mode,
  --use-* etc.) using the authoritative src/client/usage.c flags.
- Fix `perf-analyst` benchmark flags (-m -c -> -j -z) and point at
  benchmark/bench.py instead of stale numbers.
- Correct `code-explainer` (no getopt_long; --sendfile not -f) and
  version drift in the release skill (1.1.0 -> 2.20.0).
- Replace GitHub/`gh` workflows with Gitea/`tea` (PRs target dev; issues
  via tea; branch strategy updated in all agents).
- Use the built-in `-DSANITIZER=address|thread` CMake option instead of
  hand-rolled -fsanitize flags.
- Add `-p 8080 --allow-unauthenticated` to plain-TCP server examples.
- Merge the redundant security-screener into security-auditor; drop the
  duplicate (16 agents remain).

Repo hygiene: gitignore `root/` and `test_partial_install_tmp/`, remove
the empty leftover trees, delete the tracked scratch scripts tmux.sh and
to_one_file.py, and note the compile_commands.json symlink in README.

.opencode/agents/code-explainer.md

@@ -27,7 +27,7 @@ FastSync is a file synchronization tool (like rsync, but faster). It transfers f
 cmake -B build -S . && cmake --build build -j$(nproc)
 
 # Server (TCP mode)
-./build/server
+./build/server -p 8080 --allow-unauthenticated
 
 # Client (TCP mode)
 ./build/client --source-dir /path/to/send --dest-dir /path/to/receive --save-to-disk
@@ -37,13 +37,13 @@ cmake -B build -S . && cmake --build build -j$(nproc)
 
 # Run tests
 ./build/tests          # unit tests
-python3 test.py        # integration tests
+python3 -m pytest tests/integration/ -n 4 --dist=load -m "not setpriv"   # integration tests
 ```
 
 ## Code Walkthrough
 
 ### Client Entry Point (`src/client/client_cli.c`)
-- Parses CLI arguments using `getopt_long`
+- Parses CLI arguments using a custom option-table parser (`OPTION_TABLE` in `src/client/client_cli.c`); there is no `getopt*` usage
 - Creates `Config` struct with all options
 - Detects SSH destinations (contains `:`)
 - Calls into `client_send.c` for the actual transfer
@@ -109,7 +109,7 @@ Collection of files for batch transfer. Serialized with file count, then per-fil
 zstd streaming compression via `ZSTD_compressStream2`/`ZSTD_decompressStream`. Compression happens per-chunk in the sender stage. Level 1-22 (default 5). Streaming means memory usage stays bounded regardless of file size.
 
 ### "How does sendfile() work?"
-On Linux, `sendfile()` copies data directly from kernel file buffer to socket, bypassing userspace. ~2x faster for large files. Enabled with `-f` flag. Only works with TCP (not SSH, not compression).
+On Linux, `sendfile()` copies data directly from kernel file buffer to socket, bypassing userspace. ~2x faster for large files. Enabled with `--sendfile` (long form only). Only works with TCP (not SSH, not compression).
 
 ### "How does incremental sync work?"
 Client sends file metadata (path, size, mtime) to server. Server checks if destination file has same size+mtime. If match, server responds `STATUS_OK` (skip). If mismatch, server responds `STATUS_NEXT` (send).
@@ -138,7 +138,7 @@ When using `tea` (the task execution agent) to run CI or tests, always set a suf
 
 ## Branch Strategy
 
-Never push directly to `main`. All changes must be developed on a feature branch and merged via a pull request. Always create a new branch (`git checkout -b <branch-name>`) before making changes, push it, and open a PR with `gh pr create --fill`. Wait for CI to pass before merging.
+Never push directly to `dev` or `main`. All changes must be developed on a feature branch and merged via a pull request targeting `dev`. Create a branch (`git checkout -b <branch-name>`), push it, and open the PR with `tea pr create --repo TapTap/FastSync --base dev --head <branch-name>`. Wait for CI to pass before merging.
 
 ## Dependency Installation