feat(tools/asf-svn): ASF SVN-based tool adapter (svn.apache.org + dist.apache.org), full capability surface like tools/github

[potiuk]

Add tools/asf-svn/ as a complete tool adapter for the Apache Software Foundation's SVN-based infrastructure — the SVN counterpart to tools/github/ and the tools/gitlab/ bridge (#305). Where #602 lands the generic Subversion source-control binding, this issue packages that binding plus the ASF-specific surface into a first-class tool an ASF project can name under Tools enabled, the same way it would name github.

ASF SVN is not a forge with issues/PRs/boards, so this adapter implements the subset of the tool capability table that maps, plus the things that are unique to ASF infra:

Capabilities to provide (mirror tools/github/tool.md where applicable):

• Source control (VCS) — source-control.md with the SVN binding (checkout/update/svn diff/svn status/svn log/svn blame/file-at-revision/commit). Reuses the VCS abstraction from feat(tools/subversion): Apache Subversion (SVN) support — ASF svn.apache.org / dist.apache.org #602; documents the centralized model divergences (no local commits, no worktree, server-side branches/tags as directory copies).
• CLI / API operations — operations.md: the svn recipes the skills invoke, plus the https://svn.apache.org/repos/asf/<project> layout (trunk / branches / tags).
• Credentials — ASF committer auth pre-flight (the svn auth / ~/.subversion equivalent of gh auth status that a skill's Step 0 runs).
• Release distribution — dist.apache.org-aware helpers: stage a candidate under dist/dev/<project>, promote to dist/release/<project> on a successful vote, and prune old releases per ASF policy. This is the ASF-specific payoff — every ASF release ships through this SVN area, and no GitHub/GitLab tool can touch it.
• Authorization / roster (read) — resolve committer/PMC membership and write access from the ASF authorization model (asf-authorization-template, project LDAP groups) so the skills know who may commit/release. Pairs with the apache-projects MCP roster source.
• Website / docs publishing (optional) — projects that publish their site via SVN (svnpubsub / staging) get a publish helper.

Write paths (commit, dist promote/prune) stay gated on explicit user confirmation in the calling skill, exactly as the GitHub tracker write paths are.

Why: The ASF is the framework's home turf, and a large set of TLPs still run source and/or releases on SVN — dist.apache.org is SVN for every ASF project regardless of where its code lives, so even a GitHub-hosted ASF project needs this adapter to steward its release flow. A GitHub-only tool surface is structurally blind to ASF release infrastructure. Packaging it as a named tool (not just a raw VCS binding) lets an ASF adopter mix-and-match: e.g. GitHub issues + asf-svn source control + asf-svn release distribution.

Reference:

• ASF SVN: https://svn.apache.org/repos/asf/
• ASF dist area: https://dist.apache.org/repos/dist/
• ASF release distribution policy: https://infra.apache.org/release-distribution.html
• Tool-adapter shape to mirror: tools/github/tool.md and the new tools/github/source-control.md
• Generic SVN VCS binding this builds on: feat(tools/subversion): Apache Subversion (SVN) support — ASF svn.apache.org / dist.apache.org #602; ASF infra bootstrap context: 3. Infrastructure — source control & GitHub #526