Give the fork a release number independent of the upstream version

[typeless]

Both fork releases so far collided on the upstream number — v5.8.0-agent and v5.8.0-agent-putup describe the same 5.8.0 base, so each new release had to invent another suffix instead of incrementing. There was no room left for a third.

Why not renumber MAJOR/MINOR/PATCH

The upstream triple is not cosmetic — it is read as upstream-semantic in five places:

Consumer	Use
teraterm/ttpset/ttset.c:586	RunningVersion = MAJOR*10000 + MINOR — compat gate
teraterm/ttpset/ttset.c:575,2090	TERATERM.INI Version key, read + written
teraterm/ttpcmn/ttcmn_static.c:55	shared-memory filemap name ttset_memfilemap_5_8_0
teraterm/ttpmacro/ttl.cpp:2965	TTL cur_major/cur_minor, exposed to user macros
5 × *-version.rc	FILEVERSION / PRODUCTVERSION numeric fields

Renumbering to a fork-owned 1.0.0 would send RunningVersion backwards (50008 → 10000), silently flipping upstream compat branches, and break user macros testing cur_major >= 5.

Change

The upstream triple stays the base; TT_VERSION_SUBSTR carries the fork's own semver, starting at 1.0.0 on the first putup-only tree. Releases increment independently; a rebase moves the base without disturbing the counter.

The dash in agent-1.0.0 is load-bearing: svnrev.pl:367 splices SUBSTR straight into $version, which becomes OutputBaseFilename, so a space would put spaces in the installer and zip filenames.

Verification

Ran the actual version pipeline:

$ perl buildtools/svnrev/svnrev.pl --root . --isl … --header …
#define Version            "5.8.0-agent-1.0.0"
#define VersionInfoVersion "5.8.0.0"
#define Revision           "cda4991"

derived installer basename:
teraterm-5.8.0-agent-1.0.0-x64-20260720_151250-cda4991-noname-snapshot

• VersionInfoVersion still reduces to the numeric quad 5.8.0.0, so the five .rc version fields stay valid.
• Filenames are space-free.
• Nothing in the tree hardcodes the old string — grep across *.sh, *.yml, *.iss, *.py, *.pl, Tupfiles found zero hits; every consumer derives from tt-version.h.

Not verified locally: that it compiles (string macro; the Windows build needs CI — llvm-rc cannot run in the local sandbox). This PR's CI is the check.

Next: tag v5.8.0-agent-1.0.0 once this is on main.

https://claude.ai/code/session_01YEkLFtTYQZuQHgQP5qYtq7