Add daemon startup smoke test and let it run on a PC in debug_mode

v0.11.0 shipped a daemon binary that built fine but didn't actually serve
a working frontend. CI was green. Nothing in the pipeline asserted that
the built binary comes up and serves something.

Add daemon/tests/smoke.rs as an integration test that spawns the built
binary against a tempdir-backed config with debug_mode = true, picks an
ephemeral port, and asserts:

- GET /index.html is 2xx and the decompressed body contains "Rayhunter"
- GET /api/qmdl-manifest is 2xx
- the daemon exits cleanly on SIGINT

Captures the daemon's stderr into a buffer so startup/shutdown failures
print actionable context instead of just "did not start listening".

Runs as part of the regular cargo test invocation, no new CI job.

For the smoke test (and #826) to work, the daemon needs to come up on a
PC without /dev/diag, a screen, or wpa_supplicant. The DIAG read thread,
display driver, and key input were already gated on debug_mode. Gate the
two remaining device-dependent workers the same way:

- run_battery_notification_worker (polls battery sysfs paths)
- wifi_station::run_wifi_client (talks to wpa_supplicant)

doc/installing-from-source.md gains a "Running the daemon on your PC"
section. doc/porting.md drops its duplicate debug_mode line and links to
the new section.

Closes #826.

Cargo.lock

@@ -274,6 +274,19 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "async-compression"
+version = "0.4.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93c1f86859c1af3d514fa19e8323147ff10ea98684e6c7b307912509f50e67b2"
+dependencies = [
+ "compression-codecs",
+ "compression-core",
+ "futures-core",
+ "pin-project-lite",
+ "tokio",
+]
+
 [[package]]
 name = "async-executor"
 version = "1.13.3"
@@ -992,6 +1005,23 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "compression-codecs"
+version = "0.4.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "680dc087785c5230f8e8843e2e57ac7c1c90488b6a91b88caa265410568f441b"
+dependencies = [
+ "compression-core",
+ "flate2",
+ "memchr",
+]
+
+[[package]]
+name = "compression-core"
+version = "0.4.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc14f565cf027a105f7a44ccf9e5b424348421a1d8952a8fc9d499d313107789"
+
 [[package]]
 name = "concurrent-queue"
 version = "2.5.0"
@@ -4988,6 +5018,7 @@ version = "0.12.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eabf4c97d9130e2bf606614eb937e86edac8292eaa6f422f995d7e8de1eb1813"
 dependencies = [
+ "async-compression",
  "base64 0.22.1",
  "bytes",
  "futures-core",