add tclsfe-x64.exe (win32-x86_64) + AGENTS.md scaffolding

- tclsfe-x64.exe: Tcl 9.1b0 single-file runtime by Ashok P. Nadkarni (github.com/apnadkarni/tcl-sfe releases) with statically-linked Thread/twapi/sqlite3/tdbc::odbc - pinned here as the static-package verification runtime for shellspy G-058 (punkshell boot honouring statically-linked runtime packages); upstream is a moving beta so the exact binary is preserved (sha1 3a1e2f03e1962dd7c65d00aa40701a40721bc5a6)
- AGENTS.md: repository scaffolding - purpose (punkshell-specific pinned binary artifacts), layout/checksum contract (sha1sums.txt via src/build_sha1sums.tcl, git-add before summing, artifacts immutable), agent ownership rules, retrieval consumers (shellspy bin/runtime.cmd, mapvfs.config)

Assisted-by: harness=claude; primary-model=claude-fable-5; api-location=anthropic.com

AGENTS.md

@@ -0,0 +1,63 @@
+# punkbin — punkshell binary artifact repository
+
+## Purpose
+
+Pinned binary artifacts for the punkshell project (github/gitea: jn/shellspy - the
+project is punkshell; "shellspy" is a legacy repo name): per-platform Tcl runtime
+executables used as the basis for building punkshell kits/zipkits, plus selected
+build tools. This repository exists so that build and test environments can retrieve
+exact, checksummed runtime binaries instead of depending on moving upstream releases
+(e.g. beta runtimes such as tclsfe-x64.exe from github.com/apnadkarni/tcl-sfe) or on
+binaries that exist only on one developer machine.
+
+This artifact repository is specific to the punkshell project.
+
+## Ownership
+
+- Owned by the punkshell project maintainer.
+- Agents may add artifacts and update checksums when the punkshell project work
+  calls for it (e.g. preserving a runtime that punkshell tests depend on) - report
+  additions in the completion summary.
+- Agents must not modify or delete existing binaries; superseding a runtime means
+  adding the new file, not overwriting the old one.
+
+## Local Contracts
+
+- Layout: one folder per platform (`win32-x86_64/`, `linux-x86_64/`, `linux-arm/`,
+  `macosx/`, `freebsd-arm64/`, ...), optional `tools/` subfolders for build tooling
+  (e.g. zig archives). `src/` holds maintenance scripts for this repository itself.
+- Every platform folder (and tool subfolder) carries a `sha1sums.txt` with one
+  `<sha1> *<filename>` line per artifact (binary-mode marker `*`).
+- `sha1sums.txt` is regenerated with `tclsh src/build_sha1sums.tcl` from the repo
+  root. The script only sums git-tracked files - `git add` a new artifact BEFORE
+  running it. It reports NEW/SAME/CHANGED per file; a CHANGED line for an existing
+  artifact is a red flag (artifacts are immutable - investigate, don't commit).
+- Binaries are deliberately committed here - this repo is the exception to the
+  punkshell source repo's no-committed-binaries direction (shellspy G-004): the
+  source repo points at this one (G-006 retrieval direction) instead of carrying
+  binaries itself.
+- Runtime expectations (see README.md): self-contained Tcl interpreters usable as
+  kit bases; punk runtimes load Tk as an extension (no separate Tk runtime).
+  Runtimes with statically-linked packages (e.g. tclsfe-x64.exe: Thread, twapi,
+  sqlite3, tdbc) are supported by punkshell boot as of shellspy G-058.
+
+## Work Guidance
+
+- Adding a runtime: copy it into the platform folder, `git add` it, run
+  `tclsh src/build_sha1sums.tcl`, verify the NEW line's checksum, commit with a
+  message recording provenance (upstream URL/version/build source).
+- Consumers: the punkshell project retrieves runtimes into its
+  `bin/runtime/<platform>/` via `bin/runtime.cmd` or manual copy; punkshell's
+  `src/runtime/mapvfs.config` maps runtimes to vfs payloads.
+- Do not push on an agent's initiative - the remote is the project's upstream
+  artifact store; the maintainer controls what is published.
+
+## Verification
+
+- `tclsh src/build_sha1sums.tcl` reports SAME for every pre-existing artifact and
+  NEW only for intended additions.
+
+## Child DOX Index
+
+(None - flat platform folders with artifacts, checksums and README.md; `src/` is a
+single maintenance script.)

win32-x86_64/sha1sums.txt

@@ -1,5 +1,6 @@
 22e11146eab873e3fcfd3453938800461212c497 *tclkit86bi.exe
 83a7fe3d3ff81b4f8432f298a1caeae29a0c430e *tclkit902.exe
+3a1e2f03e1962dd7c65d00aa40701a40721bc5a6 *tclsfe-x64.exe
 51d00ccc2e3c59e9b38c4607c928cb9d202d6c75 *tclsh901k.exe
 ec9d058279c47e9abe27443793d864ffaf84a672 *tclsh901t.exe
 9e1251d256ca69eefc8b2b8344d07b030bf542dd *tclsh902z.exe