feat(v1.1.7-email-outbound): SMTP send/send_html

Outbound email reachable from scripts as email::send(#{...}) (plain
text) and email::send_html(#{...}) (multipart text + HTML). Backed by a
lettre SMTP relay configured from PICLOUD_SMTP_HOST/PORT/USER/PASSWORD/
TLS/TIMEOUT_SECS; if HOST/USER/PASSWORD aren't all set the service runs
in disabled mode (every send throws NotConfigured, warned at startup).

- EmailService trait + OutboundEmail DTO (picloud-shared);
  EmailServiceImpl + EmailTransport seam + lettre transport
  (manager-core), wired into the Services bundle and Rhai engine.
- Capability::AppEmailSend (→ script:write); seven-scope commitment held.
- Required-field + RFC5322-ish address validation; 25 MB per-message cap
  (PICLOUD_EMAIL_MAX_MESSAGE_BYTES). reply_to defaults to from.
- Per-call connection (pooling deferred to v1.2); no per-app from
  validation (operator's SMTP/SPF/DKIM concern).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -573,7 +573,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6f8c3e73077b4b4a6ab1ea5047c37c57aee77657bc8ecd6f29b0af082d0b0c07"
 dependencies = [
  "chrono",
- "nom",
+ "nom 7.1.3",
  "once_cell",
 ]
 
@@ -715,6 +715,22 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "email-encoding"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9298e6504d9b9e780ed3f7dfd43a61be8cd0e09eb07f7706a945b0072b6670b6"
+dependencies = [
+ "base64",
+ "memchr",
+]
+
+[[package]]
+name = "email_address"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e079f19b08ca6239f47f8ba8509c11cf3ea30095831f7fed61441475edd8c449"
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -1010,6 +1026,17 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "hostname"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "617aaa3557aef3810a6369d0a99fac8a080891b68bd9f9812a1eeda0c0730cbd"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "windows-link",
+]
+
 [[package]]
 name = "http"
 version = "1.4.0"
@@ -1320,6 +1347,34 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
+[[package]]
+name = "lettre"
+version = "0.11.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0da65617f6cb926332d039cb578aad56178da86e128db6a1b09f4c94fa5b3349"
+dependencies = [
+ "async-trait",
+ "base64",
+ "email-encoding",
+ "email_address",
+ "fastrand",
+ "futures-io",
+ "futures-util",
+ "hostname",
+ "httpdate",
+ "idna",
+ "mime",
+ "nom 8.0.0",
+ "percent-encoding",
+ "quoted_printable",
+ "rustls",
+ "socket2",
+ "tokio",
+ "tokio-rustls",
+ "url",
+ "webpki-roots 1.0.7",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.186"
@@ -1469,6 +1524,15 @@ dependencies = [
  "minimal-lexical",
 ]
 
+[[package]]
+name = "nom"
+version = "8.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df9761775871bdef83bee530e60050f7e54b1105350d6884eb0fb4f46c2f9405"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "normalize-line-endings"
 version = "0.3.0"
@@ -1795,6 +1859,7 @@ dependencies = [
  "chrono-tz",
  "cron",
  "data-encoding",
+ "lettre",
  "picloud-executor-core",
  "picloud-orchestrator-core",
  "picloud-shared",
@@ -2082,6 +2147,12 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "quoted_printable"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "478e0585659a122aa407eb7e3c0e1fa51b1d8a870038bd29f0cf4a8551eea972"
+
 [[package]]
 name = "r-efi"
 version = "5.3.0"
@@ -2385,6 +2456,7 @@ version = "0.23.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ef86cd5876211988985292b91c96a8f2d298df24e75989a43a3c73f2d4d8168b"
 dependencies = [
+ "log",
  "once_cell",
  "ring",
  "rustls-pki-types",