chore: remove vendored antiflood-tokens and identity-management modules

[iduartgomez]

Summary

Removes the `modules/antiflood-tokens/` and `modules/identity-management/` directories from freenet-core. These crates have been moved to the freenet-email repository (see freenet/mail#10), which is their only consumer.

These modules were never part of freenet-core's workspace `members` list — they lived in `modules/` as orphaned, independently-built crates with their own Makefiles, used only by freenet-email's legacy build pipeline.

What was removed

• `modules/antiflood-tokens/` — nested workspace containing:
  • `contracts/token-allocation-record/` (freenet contract)
  • `delegates/token-generator/` (freenet delegate)
  • `interfaces/` (shared `freenet-aft-interface` crate)
  • standalone `Cargo.toml` (nested workspace) and `Makefile`
• `modules/identity-management/` — freenet delegate + tool binary

Verification

`cargo check --workspace` compiles 236 crates clean after the removal — no dangling references anywhere in freenet-core (verified across all `.toml`, `.rs`, `.md`, `.sh`, `*.yml` files). The only references were self-referential Makefiles inside the deleted directories themselves.

Cross-references

• Phase 0: productionize build pipeline and bring workspace to green mail#10 — the PR that vendors these crates into freenet-email, wires up build tasks, and brings that workspace to a fully-green state. Merge that first (or alongside) so there's no window where the code exists in neither repo.

Test plan

• `cargo check --workspace` clean (236 crates)
• CI build in freenet-core should be unaffected since these modules were never part of the main workspace

[github-actions]

Rule Review: Clean deletion PR, no code violations

Rules checked: git-workflow.md, code-style.md
Files reviewed: 23 (all deletions — no new code introduced)

Warnings

None.

Info

• commit message — The commit body conveys the required information (what, why, verification), but doesn't use the prescribed ## Problem / ## Solution / ## Testing / ## Fixes section headers from git-workflow.md. If the GitHub PR body also lacks these headers, it would technically be a format violation. The substance is there; only the markdown structure is informal. (rule: git-workflow.md — WHEN creating a PR)

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This is a pure deletion PR removing orphaned, non-workspace vendored modules. No production code was added or modified, so code-style rules (.unwrap(), spawns, channels, retry loops, etc.) have nothing to apply to. The chore: commit prefix is correct for this type of change.

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Rule review against .claude/rules/. WARNING findings block merge.