Merge upstream v1.2.19 into the fork

Merges upstream tag v1.2.19 (9e39a50) into merge/upstream-1.2.18 (991853f).
Unlike the 1.2.15->1.2.18 replay, bc3de30 is a true ancestor of our branch via
a9b4f89, so this is an ordinary three-way merge with merge-base bc3de30.

Delta: 36 files, +3265/-163, the Tor onion transport (managed Tor, signed
direct onion endpoints, onion-only dial mode) and the nHDNext restore fix.
src/main.cpp, main.h, script.cpp/h and db.cpp/h are byte-identical between the
two tags, and the poll() socket loop carries no diff hunks, so the merge is
consensus-neutral and the soak-tested socket paths are unchanged. relay/ is
untouched; the payout ledger (rpc.cpp) is untouched.

7 conflict blocks in 6 files, resolved as follows.

Makefile -- VERSION. Ours: stays 1.2.19+sec with the naming comment updated,
so artifacts from this tree cannot be mistaken for the upstream release.

src/Makefile, src/makefile.mingw -- HEADERS list. Ours (no market.h) plus
their tor.h. NODE_OBJS auto-merged correctly: no market.o, tor.o present.

src/selftest.cpp -- known-tests list. Union: payout-ledger (ours) and
managed-tor (theirs).

src/main_gui.cpp -- one block. Our /dumpaddresses kept; their
BtfStopManagedTor() on the StartNode failure path taken. The /rvrelay pin,
/noannounce and the marketplace removal auto-merged and were verified intact.

src/nostr.cpp -- two blocks in ResolveDescriptor. Signature takes both
out-params (our fExchangeOk, their rawOut). The body keeps our
drain-to-EOSE read -- returning early poisons the pooled socket for the next
caller -- and adds their rawOut capture. Our TLS 1.2 floor
(SSL_CTX_set_min_proto_version) is untouched by this merge; upstream 1.2.19
still has no floor of its own.

Upstream's release commit also added four build logs and a compiled Python
cache (build-1219.log, build-17.log, build-appimage.log, build-node.log,
scripts/__pycache__/bitflash_chain.cpython-313.pyc). Removed here; they are
build output, not source.

1 files changed, 115 insertions, 0 deletions

diff --git a/docs/site.md b/docs/site.md
new file mode 100644
index 0000000..9526a61
--- /dev/null
+++ b/docs/site.md
@@ -0,0 +1,115 @@
+# Public Site Contract
+
+The public Bitflash sites are generated from this repository. If a deployed
+page and the source disagree, the deployed page is stale.
+
+## Canonical Navigation
+
+Every public page should use the same top navigation:
+
+| label | target |
+|---|---|
+| home | `https://bitflash.network/` |
+| code | `https://git.bitflash.network/bitflash/bitflash` |
+| docs | `https://docs.bitflash.network/` |
+| downloads | `https://releases.bitflash.network/` |
+| explorer | `https://explorer.bitflash.network/` |
+| status | `https://status.bitflash.network/` |
+
+The `code` link intentionally points at the repository, not the Forgejo
+instance root. A visitor choosing "code" wants the source tree.
+
+## Documentation Pages To Publish
+
+The docs index should expose these source files:
+
+| page | source | why it matters |
+|---|---|---|
+| Manual | `README.md` | run, mine, recover, operate |
+| Key derivation and address format | `docs/derivation.md` | independent wallet recovery |
+| Release verification | `docs/release-verification.md` | pinned signing-key flow |
+| Dependencies | `docs/dependencies.md` | pinned secp256k1/RandomX supply chain |
+| Rendezvous and .btf addressing | `docs/rendezvous.md` | network design and caveats |
+| Tor mode | `docs/tor.md` | `-tor`, `-socks`, onion relay operation |
+| Fair launch verifier | `docs/fair-launch.md` | no-premine launch audit |
+| UTXO set commitment | `docs/utxo-commitment.md` | deterministic supply/root audit |
+| UTXO inclusion proofs | `docs/utxo-proofs.md` | proof for one unspent output |
+| Mining calculator | `docs/mining-calculator.md` | local WhatToMine-style estimates |
+| Public pool directory | `docs/pool-directory.md` | `pool_status.json`, `pools.json`, ranking |
+
+## Release Mirror Aliases
+
+Each release remains under its versioned directory:
+
+```text
+https://releases.bitflash.network/v1.2.19/SHA256SUMS
+https://releases.bitflash.network/v1.2.19/SHA256SUMS.asc
+```
+
+The release root should also alias the latest files:
+
+```text
+https://releases.bitflash.network/SHA256SUMS
+https://releases.bitflash.network/SHA256SUMS.asc
+https://releases.bitflash.network/Bitflash-latest-windows.zip
+https://releases.bitflash.network/Bitflash-latest-x86_64.AppImage
+https://releases.bitflash.network/bitflash-node-latest-x86_64
+```
+
+The aliases are convenience only. Verification must still require the pinned
+release key documented in `docs/release-verification.md`.
+
+## Static Explorer
+
+`scripts/build-explorer.py` writes a static explorer with no backend:
+
+```text
+index.html
+style.css
+explorer.js
+logo.png
+blocks.json
+block/<height>.json
+```
+
+Serve it with a strict content policy:
+
+```text
+default-src 'none';
+img-src 'self';
+style-src 'self';
+script-src 'self';
+connect-src 'self';
+base-uri 'none';
+form-action 'none';
+frame-ancestors 'none';
+```
+
+The viewer must never use `innerHTML` for chain data. A malicious transaction
+must be rendered as text, not interpreted as markup.
+
+## Cache Policy
+
+Recommended defaults:
+
+| path | cache |
+|---|---|
+| HTML pages | `public, max-age=0, must-revalidate` |
+| `status.json` | `no-store` |
+| `blocks.json`, `block/*.json` | `public, max-age=0, must-revalidate` |
+| release assets | `public, max-age=14400, must-revalidate` |
+| `SHA256SUMS`, signatures, keys | `public, max-age=0, must-revalidate` |
+
+## Security Headers
+
+Recommended for all static pages:
+
+```text
+Strict-Transport-Security: max-age=31536000; includeSubDomains
+X-Content-Type-Options: nosniff
+Referrer-Policy: no-referrer
+Permissions-Policy: interest-cohort=(), geolocation=(), camera=(), microphone=()
+```
+
+Forgejo has its own application headers and should not blindly inherit the
+static-site CSP.